[WEB-26] Create delete function for removing files and folders

[brian2w]

Why the changes are required?

Currently, there is no way to delete files and folders in the CMS.

Changes

• Added delete file button to sidebar
• Added delete confirmation modal
• Opening a folder is now a double click (rather than a single click)
• Single click 'selects' the folder (indicator still needed) - temporary indicator makes folder red when selected (sorry for the unaesthetic colour atm)

Screenshots

Comments

• Need to contact backend team regarding recursively deleting contents inside a folder

[lauraw0]

Looks great!! :D We'll ignore the changes in whitespace for now (creating a prettier template is on my todo list somewhere) but if you could make these small ux changes that would be awesomeee:

• when the user clicks away from the folders and files (onBlur) the selectedFile should revert to null
• when the user presses on the delete button on the keyboard (onKeyPress) the same delete functionality should apply