Add support for more file types

[thefirstofthe300]

My team needs support for Ruby files, Dockerfiles, Gemfiles, and Groovy files. This commit adds support for all of these file types.

[googlebot]

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[googlebot]

CLAs look good, thanks!

[x1ddos]

Thanks! A few comments.

[x1ddos]

Just a couple nits.
Thanks for swapping Google Inc. => Google LLC. Forgot to do it.

[x1ddos]

Thank you!