Audit gitlab-rails dependencies for Ruby 3 compat

The goal is to make sure that gems we use in gitlab-rails have test coverage for Ruby 3 and no known incompatibilities.

This is likely going to be on a best-effort basis, considering the volume of dependencies to look at.

Update 2022-09-09

Current status:

Review complete (Y/N)	Percent
N	55.32%
Y	44.68%

Action required	Percent
?	57.45%
N	32.77%
Y	9.79%