Add ARM Support

[jhollowe]

Requirements

• Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• All new code requires tests to ensure against regressions

Description of the Change

Add ARM support (matching the scope(s) of most ARM language packages)

Alternate Designs

Most ARM compilers support other comment characters (e.g. "\" or ";"), but "@" seems to be the most universally accepted single-line comment character.

Benefits

Use of keyword comments to better notate assembly code

Possible Drawbacks

None

Applicable Issues

[rsese]

Thank you very much for the contribution!

We generally don't accept modifications for snippets in the language packages since they are easily overridden and we expect that people will do so for their own purposes. We provide instructions on how people can create their own snippets in the Flight Manual, and viewing a language package that provides snippets allows you and anyone else to copy the current version as a starting place for creating your own.

Thanks again for the suggestion but we're going to leave things as they are for now unless we're fixing a current snippet that produces invalid code.