Delete the SVNRepository class, we no longer support SVN and so no longer need it.
<rdar://problem/125716794>
Pull request: https://github.com/WebKit/WebKit/pull/26674
Committed 276883@main (e7f669c3752c): <https://commits.webkit.org/276883@main> Reviewed commits have been landed. Closing PR #26674 and removing active labels.