Add dynamic selectors to method completion

[Bawnorton]

Previously custom selectors do not appear in the method autocomplete suggestion window, this adds their ids to the autocomplete suggestions (below normal methods) and optionally populates additional annotations (I have implemented this for @Desc based on the handling of MIXINEXTRAS:EXPRESSION). I would perhaps prefer to put this in the selector definition itself rather than the parser, however, that would require a bit of a redesign of how custom selectors exist in mcdev so I left it as-is.

Example of what this looks like, where before neither @Desc nor @MixinSquared:Handler would appear as a suggestion

Screen.Recording.2026-05-01.at.12.28.12.mov