add custom allocator to make sure that vector arrays go into PSRAM when availeable

[softhack007]

animartrix-esp32/ANIMartRIX.h

Lines 105 to 106 in bd556ce

	std::vector<std::vector<float>> polar_theta; // look-up table for polar angles
	std::vector<std::vector<float>> distance; // look-up table for polar distances

animartrix-esp32/ANIMartRIX.h

Lines 342 to 346 in bd556ce

	void render_polar_lookup_table(float cx, float cy) {
	polar_theta.resize(num_x, std::vector<float>(num_y, 0.0f));
	distance.resize(num_x, std::vector<float>(num_y, 0.0f));

We need better control of array placement for boards with PSRAM. Normally on esp32, big allocations automatically go into PRSAM. However due to the 2D vector definitions used for the lookup tables, each "row" vector is only 256 bytes and the framework will only put these into PSRAM if there is not enough RAM or PSRAM is very fast (opi_opi mode).

The standard way with vectors seems to be: add a custom allocator to the vector declaration , like the "Mallocator" in this example:
https://learn.microsoft.com/en-us/cpp/standard-library/allocators?view=msvc-170

For compatibility with the vector template class, it seems that operator== and operator!= must be implemented by the Mallocator, too.

The custom allocator should use ps_malloc() and free().

The custom allocator code should only be used on ESP32 with PSRAM, i.e.

#ifdef ESP32
#if defined(BOARD_HAS_PSRAM) && defined(CONFIG_IDF_TARGET_ESP32S3)
[...]
#endif
#endif

[softhack007]

@ewowi and @netmindz: can you review the proposed changes in PR #2 ? I don't have much experience with C++ vectors, so I'm basically doing this in "blind flight" mode.