Add language: ato

[iopapamanoglou]

Add a new language to Linguist, named ato, for the file extension .ato.
Docs @ https://atopile.io

Description

ato is the language of the atopile project.
It's created to describe electronics designs in code instead of schematics.

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*.ato+module
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/atopile/packages/blob/main/packages/rp2040/RP2040.ato
    • Sample license(s): MIT
  • I have included a syntax highlighting grammar: https://github.com/atopile/ato-syntax
  • I have added a color
    • Hex value: #F95015
    • Rationale: official atopile orange color (used in logo and other marketing)
  • I have updated the heuristics to distinguish my language from others using the same extension.