Fix for selecting and deleting subfolders and files

[hannyle]

Description

• Subfolders and files should be all selectable by checking checkbox
• Subfolders shouldn't be deleted before deleting all files inside it
• Files should be able to select and mass delete

Related issues

GL 933 & 936 & 974

Type of change

• Bug fix (non-breaking change which fixes an issue)

Changes Made

• Added folder icon for sub-folders
• Added prefix to file's names so the file names are matched when its checkbox is selected
• Changed Display as text to Display as path to make the term more understandable
• Prevented subfolders from being deleted when clicking Delete button or selecting together with files
• Updated Changelog

Testing

• Needs testing (manual test)

Mention

• Since we have now subfolders and files in the same view, some notifications when selecting and deleting them are not clear enough and still not in correct timing/visual order
• The terms and text are still not so clear since we only have objects before, now objects could mean subfolders and `files``
  --> These things should be fixed in another PR while waiting for the UI design from @ainoc

[hannyle]

Noticed an issue with this, I will make changes

[hannyle]

Ready for review

Figured out some small bugs related to this after talking with Aino-Riikka so I will fix them here

[hannyle]

A follow-up PR will be needed when the UI design is ready, as I wrote in the Mention part

[sampsapenna]

Works nicely, and displaying only the paths of the current folder recursively is indeed more intuitive than the old behavior. Uploads into nested folders still works as well, so I didn't notice any regressions.

LGTM 👍🏼