Add language: LPC

[jlchmura]

Description

This PR adds syntax highlighting for the LPC language, a C-like language used in MUD drivers such as LDMud and FluffOS.

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.c+%28%22this_player%28%29%22+OR+%22this_object%28%29-%3E%22%29
        Note: While this search does show widespread use of LPC, it understates the popularity of the language. The nature of most mudlibs is such that they are stored in private repos.
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/jlchmura/lpc-language-server/blob/main/server/src/tests/cases/compiler/
    • Sample license(s):
      • MIT
  • I have included a syntax highlighting grammar: https://github.com/jlchmura/lpc-language-server/tree/main/syntaxes
  • I have added a color
    • Hex value: #ffb100
    • Rationale: It is reminiscent of the amber screens that were in use when many MUDs got their start
  • I have updated the heuristics to distinguish my language from others using the same extension.

[jlchmura]

Note to the maintainers: I was not able to write a heuristic that could handle samples/c/nightmare.h since C and LPC are so similar in that regard. Do you recommend removing LPC from the .h extension, and let the user override via gitattributes linguist-language?

[jlchmura]

This PR will close #7178