Raise TypeError in Livecheck DSL methods, expand tests, improve documentation comments

[samford]

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This adds raise TypeError logic to the Livecheck DSL methods when an invalid argument type is provided. This change brings the existing methods in line with the #strategy method added in #8156. Relevant tests have been added as well.

This also makes some changes to the existing tests for the Livecheck DSL, to better test the methods.

Past that, this reworks the documentation comments a bit and adds @param/@return information.

[samford]

Failed examples:

rspec ./test/utils/github_spec.rb:7 # GitHub::search_code queries GitHub code with the passed parameters

1969 examples, 1 failure, 4 pendings

brew tests worked fine locally, so I'll run CI again after awhile.

Edit: Everything passes after running this again, so it appeared to be an intermittent failure.

[MikeMcQuaid]

Makes sense, thanks again @samford!