Fix CommitUI.getSelectedFiles()
This method is used to restrict the files that can be potentially
committed to those covered by the user's resource selection. If a
container is selected, all modified files under that container are
to be included in a commit.
Previous code started off with the modified files as known in git,
then tried to figure out which resource such a file was in Eclipse,
and then checked if that resource was contained by any of the selected
resources. It failed to reliably identify matches when a file appeared
as several resources in the Eclipse resource tree.
The new code swaps the logic around. It starts with the resource
selection and finds the repository-relative paths for all, and then
filters the modified files as known in git.
Bug: 535796
Change-Id: I0b77876ed3913cac987a07444c9de1e6a43e69ee
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>