Change the extension from .cpp to .hpp in the files that aren't compilation targets

[selissia]

The files GenericThreadStackManagerImpl_OpenThread.cpp and GenericThreadStackManagerImpl_FreeRTOS.cpp are not compilation targets, they are used in the #include statements by other .cpp files. Various IDEs and tools are often configured to treat files with .cpp extension as compile targets, such naming creates conflicts. This PR renames the above files to carry the .hpp extension instead of .cpp.

[github-actions]

PR #26374: Size comparison from de1c64a to 94c9a9a

Increases (2 builds for cc32xx, qpg)

platform	target	config	section	de1c64a	94c9a9a	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	.debug_info	19522697	19522699	2	0.0
qpg	lighting-app	qpg6105+debug	(read/write)	1167808	1167816	8	0.0
			.text	614908	614916	8	0.0

Full report (13 builds for bl602, bl702, cc32xx, k32w, linux, mbed, qpg)

platform	target	config	section	de1c64a	94c9a9a	change	% change
bl602	lighting-app	bl602	(read/write)	1354838	1354838	0	0.0
			.bss	87886	87886	0	0.0
			.data	9648	9648	0	0.0
			.text	1035790	1035790	0	0.0
		bl602+rpc	(read/write)	1401114	1401114	0	0.0
			.bss	95934	95934	0	0.0
			.data	10040	10040	0	0.0
			.text	1067146	1067146	0	0.0
bl702	lighting-app	bl702		0	0	0	0.0
			(read only)	3358	3358	0	0.0
			(read/write)	1185199	1185199	0	0.0
			.bleromro	6342	6342	0	0.0
			.bleromrw	124	124	0	0.0
			.boot2	328	328	0	0.0
			.bss	67601	67601	0	0.0
			.bss_psram	24368	24368	0	0.0
			.comment	48	48	0	0.0
			.data	3952	3952	0	0.0
			.debug_abbrev	1549515	1549515	0	0.0
			.debug_aranges	132776	132776	0	0.0
			.debug_frame	487884	487884	0	0.0
			.debug_info	40749398	40749398	0	0.0
			.debug_line	5293911	5293911	0	0.0
			.debug_loc	3418091	3418091	0	0.0
			.debug_ranges	372032	372032	0	0.0
			.debug_str	3675990	3675990	0	0.0
			.hbn	536	536	0	0.0
			.hbn_noinit	260	260	0	0.0
			.init	342	342	0	0.0
			.init_array	140	140	0	0.0
			.psram	0	0	0	0.0
			.riscv.attributes	47	47	0	0.0
			.rodata	106272	106272	0	0.0
			.rsvd	4	4	0	0.0
			.sha_ocram	72	72	0	0.0
			.shstrtab	304	304	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	580333	580333	0	0.0
			.symtab	175136	175136	0	0.0
			.tcm_data	28	28	0	0.0
			.tcmcode	3358	3358	0	0.0
			.text	964922	964922	0	0.0
		bl702+rpc		0	0	0	0.0
			(read only)	3358	3358	0	0.0
			(read/write)	1272755	1272755	0	0.0
			.bleromro	6342	6342	0	0.0
			.bleromrw	124	124	0	0.0
			.boot2	328	328	0	0.0
			.bss	75633	75633	0	0.0
			.bss_psram	24768	24768	0	0.0
			.comment	48	48	0	0.0
			.data	4504	4504	0	0.0
			.debug_abbrev	1702795	1702795	0	0.0
			.debug_aranges	141000	141000	0	0.0
			.debug_frame	515776	515776	0	0.0
			.debug_info	45444505	45444505	0	0.0
			.debug_line	5703342	5703342	0	0.0
			.debug_loc	3619114	3619114	0	0.0
			.debug_ranges	397064	397064	0	0.0
			.debug_str	4100399	4100399	0	0.0
			.hbn	536	536	0	0.0
			.hbn_noinit	260	260	0	0.0
			.init	342	342	0	0.0
			.init_array	156	156	0	0.0
			.psram	0	0	0	0.0
			.riscv.attributes	47	47	0	0.0
			.rodata	120112	120112	0	0.0
			.rsvd	4	4	0	0.0
			.sha_ocram	72	72	0	0.0
			.shstrtab	304	304	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	640877	640877	0	0.0
			.symtab	193424	193424	0	0.0
			.tcm_data	28	28	0	0.0
			.tcmcode	3358	3358	0	0.0
			.text	1037314	1037314	0	0.0
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	604866	604866	0	0.0
			(read/write)	204156	204156	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197568	197568	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957005	957005	0	0.0
			.debug_aranges	101104	101104	0	0.0
			.debug_frame	341416	341416	0	0.0
			.debug_info	19522697	19522699	2	0.0
			.debug_line	2666219	2666219	0	0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1488771	1488771	0	0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94291	94291	0	0.0
			.debug_str	3100491	3100491	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104346	104346	0	0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	482872	482872	0	0.0
			.symtab	287120	287120	0	0.0
			.text	498396	498396	0	0.0
k32w	contact	k32w0+release	(read only)	583164	583164	0	0.0
			(read/write)	82704	82704	0	0.0
			.bss	65888	65888	0	0.0
			.data	2192	2192	0	0.0
			.text	582628	582628	0	0.0
	light	k32w0+release	(read only)	582044	582044	0	0.0
			(read/write)	82348	82348	0	0.0
			.bss	65544	65544	0	0.0
			.data	2180	2180	0	0.0
			.text	581508	581508	0	0.0
	lock	k32w0+release	(read only)	555532	555532	0	0.0
			(read/write)	80352	80352	0	0.0
			.bss	63624	63624	0	0.0
			.data	2104	2104	0	0.0
			.text	554996	554996	0	0.0
linux	chip-tool-ipv6only	arm64	(read only)	12200732	12200732	0	0.0
			(read/write)	745112	745112	0	0.0
			.bss	34392	34392	0	0.0
			.data	3008	3008	0	0.0
			.data.rel.ro	686848	686848	0	0.0
			.dynamic	560	560	0	0.0
			.got	15664	15664	0	0.0
			.init	24	24	0	0.0
			.init_array	216	216	0	0.0
			.rodata	568128	568128	0	0.0
			.text	9863908	9863908	0	0.0
	thermostat-no-ble	arm64	(read only)	2524596	2524596	0	0.0
			(read/write)	145784	145784	0	0.0
			.bss	56376	56376	0	0.0
			.data	1784	1784	0	0.0
			.data.rel.ro	78096	78096	0	0.0
			.dynamic	560	560	0	0.0
			.got	5448	5448	0	0.0
			.init	24	24	0	0.0
			.init_array	432	432	0	0.0
			.rodata	129848	129848	0	0.0
			.text	2130448	2130448	0	0.0
mbed	lock-app	CY8CPROTO_062_4343W+release	(read only)	6224	6224	0	0.0
			(read/write)	2494848	2494848	0	0.0
			.bss	216296	216296	0	0.0
			.data	5144	5144	0	0.0
			.text	1457532	1457532	0	0.0
qpg	lighting-app	qpg6105+debug	(read/write)	1167808	1167816	8	0.0
			.bss	99632	99632	0	0.0
			.data	856	856	0	0.0
			.text	614908	614916	8	0.0
	lock-app	qpg6105+debug	(read/write)	1137176	1137176	0	0.0
			.bss	94784	94784	0	0.0
			.data	852	852	0	0.0
			.text	584272	584272	0	0.0