Allow a prop format to be specified

[aaronjorbin]

What?
This updates the action to allow a repository to configure the specific formats they want included in the bot's comments.

Why?
Often times, only one format is relavent to a given repo. This also helps make the comment shorter. Including both formats makes it quite long.

How?
Using the formats input, all, git, or svn can now be specified. The default is git.

Fixes #38, #47.
See: #61 and #63

[github-actions]

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Core SVN

Core Committers: Use this line as a base for the props when committing in SVN:

Props desrosj, jorbin, noisysocks, gziolo.

GitHub Merge commits

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Co-authored-by: desrosj <desrosj@git.wordpress.org>
Co-authored-by: aaronjorbin <jorbin@git.wordpress.org>
Co-authored-by: noisysocks <noisysocks@git.wordpress.org>
Co-authored-by: gziolo <gziolo@git.wordpress.org>

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[desrosj]

Few minor changes.

[desrosj]

🚢