feat(cms): improve file tree style and behaviour
These are fixes to the react-folder-tree
to improve its clunky UI.
- Improved colouring of text and icons, including hover effects
- Hidden the confusing "close" icon
- Close control icons for one item when another item is selected (by simulating a click on the hidden "close" icon)
- Position control icons absolutely so they don't overflow pane and don't wrap
- Improved size/position of icons
- Improved size of input text when renaming an item