Rename base class for issue tracker integrations (!63019) · Merge requests · GitLab.org / GitLab

What does this MR do?

This adds the Base prefix to make it clear that this is a base class for other integrations, and not an actual integration itself.

We're also merging the EE extension module, which is a leftover from when we moved the Jira integration into CE in f177aaa5.

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[-] I have added/updated documentation, or it's not needed. (Is documentation required?)
I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
[-] I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
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I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
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[-] I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.