livecheck: update default match_data

[samford]

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livecheck's ElectronBuilder, ExtractPlist, and Sparkle strategies did not support a regex when they were originally created but I added support for a regex when a strategy block is also provided (#12449). At the time, I forgot to add the regex value to the match_data hash, so this PR updates these strategies accordingly.

Besides that, this adds missing documentation comments (e.g., # @param regex [Regexp, nil] a regex for use in a strategy block) and makes other small comment tweaks.

[BrewTestBot]

Review period will end on 2022-06-10 at 19:55:14 UTC.

[BrewTestBot]

Review period ended.