Main Window: Rename a files in file tree

[JackEAllen]

Desired Behaviour

Users have asked if it would be possible to rename files (stack, slices etc.) from the main window file tree view to improve filename descriptions where comparisons between files is required as part of their workflow

We should allow for the renaming of all files visible within the mina window file tree

Users should be able to double click a filename to rename or right click and rename.

Current Behaviour

Mantid Imaging currently does not support the renaming of files within the main window file tree view.