[git] IDEA-81563 Correctly identify Git root for submodule changes

When the submodule is changed in the super-project, the root of this
change is this super-project, not the submodule root.

In particular, this led to exception when trying to merge conflicts
when one of conflicts was the submodule.
automatically rename overloads (IDEA-131926)
inplace introduce parameter: ensure that parameter is not deleted if not all occurrences are replaced
tests: enable diff on root node, process children recursively
tests diff: ensure that only providers from leafs are collected, so the same provider appears only one in view
Remove unused imports of OptionalConfigurable
Turn automatic indentation detection off by default [CR-IC-7106]