* Make the code easier to own and maintain by being part of a topical
area of expertise rather than a generic catch-all bucket.
This also helps Gerrit team dashboards, [[mw:Git/Reviewers]]
subscription patterns, more meaningful component prefix for
[[mw:Commit_message_guidelines]].
* Prep for possible CODEOWNERS adoption.
* Prep for T166010 to give us better PSR-4 namespaces that we won't
have to break/migrate again shortly after for the above.
Bug: T225756
Change-Id: I62c701d574d2a79365b1c5350f92bef47770e3ce
051e127bdb