fix(compatibility): home and end in cursor keys mode

[tlinford]

When DECCKM is set, Home and End should also be adjusted. This builds upon the fix in #815 for vim compatibility, but should be also compatible with applications that don't expect the keys in DECCKM format.
Fixes #1182.

cc @imsnif

[imsnif]

Ah, awesome! I was going to take a look at it this week. I'll review it in the next day or two

[colemickens]

Very quick testing indicates this fixed Home/End in helix under zellij. Thanks @tlinford !

[imsnif]

@tlinford - great find! (reference: https://www.xfree86.org/current/ctlseqs.html)

I'm not sure why we removed the terminfo adjustments here though... aren't these unrelated?

[tlinford]

Adding some details to clarify how this pr hopefully solves the problem without creating regressions.
With the changes in #815, these sequences are always transformed:

• Home: ESC [ H -> terminfo entry for khome
• End: ESC [ F -> terminfo entry for kend

Most terminfos seem to define:

• khome: ESC O H
• kend: ESC O F

This fixed vim not working, and apparently many other programs read both these encodings fine. Helix on the other hand (via crossterm), does not recognize these ESC O variants.

With this change the transformation is only done when DECCKM has been set (this was already the case for the other cursor keys).

I removed the terminfo lookups since it would have been slightly annoying to attach it in that part of the code, and also because it's not being done for the existing DECCKM transformations we have, but it's worth keeping in mind that it's probably the right thing to do.