GitBranchWidget: add log debug, call later only for non-edt event

Additional investigation attempt for IDEA-113231.
According to comments, update() is not called when needed (but
updates properly on click).

(cherry picked from commit c10c7e5)
[git] Provide more correct equals/hashcode for GitStandardRemoteBranch

It should consider not only name, but the remote as well.
(cherry picked from commit b9dce99)
[git] IDEA-98693 Remember target remote & remote branch in push dialog

But only if it was changed from default one.
(cherry picked from commit 557baff)
[vcs] Fix VcsRootScanner initialization

Don't start in the post-startup activity: mappings are already
initialized at that time => VcsRootScanner will never be "ready" to
scheduleScan.

Instead register the vcs initialization request with the least
priority: at that time both the Project and mappings are initialized,
and scan can be performed right away.
(cherry picked from commit c877877)
[vcs] IDEA-95947 Don't notify about the same unregistered root twice

(cherry picked from commit f316d3b)
[vcs] IDEA-77576 Separate "Compare with Local" action from FileHistoryPanelImpl

Get all necessary data from the data context (declare a couple of
more DataKeys for that), instead of referencing to FHPI fields.

Also extract StandardDiffFromHistoryHandler to make if referable from
the action.
(cherry picked from commit b8bf5bb)
[git] make some git push classes & methods public by request of gerrit plugin author
(cherry picked from commit 6eb1962)