Add BatchRenameJob to KIO

Summary:
This job renames multiple files in one go. It takes as argument a list of
file urls, a new name containing exactly one placeholder character or
one connected sequence of placeholders, and an index number which
will replace the placeholder.
The new filenames will have a common base name and only the index
number which replaces the placeholder will differ.
For e.g. batchRename({file:///localpath/file1.c, file:///localpath/file2.c},
"new-name#", 7, '#') will rename both the file to "new-name7.c" and
"new-name8.c".

Reviewers: Frameworks, dfaure

Reviewed By: dfaure

Subscribers: apol

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D9103