chore: enable dependabot

[ragingsquirrel3]

This PR adds needed code changes to enable dependabot for dart projects. See https://github.blog/changelog/2022-04-05-pub-beta-support-for-dependabot-version-updates/ as well as linked thread where there are some questions about monorepos. Per that thread, I believe we need separate entries for all the pubspec locations, so I made a little script to generate that as I expect it to need updates when directory structure changes.

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[dnys1]

Looks good. Script could be cleaned up but not a major issue IMO. Can rewrite in Dart if you want and use Directory.list(recursive: true) to make it future proof.

[haverchuck]

This is any annoying nit, but could we put the 'updates' block in alphabetical order?
Otherwise looks good to me.

[ragingsquirrel3]

This is any annoying nit, but could we put the 'updates' block in alphabetical order? Otherwise looks good to me.

I changed the generation script to sort the output alphabetically.

[ragingsquirrel3]

Looks good. Script could be cleaned up but not a major issue IMO. Can rewrite in Dart if you want and use Directory.list(recursive: true) to make it future proof.

Good suggestion, ended up converting to a dart script to do this plus some other things.