[FileSystem Dock] Add symlink indicator and tooltip.

[bruvzg]

Adds symlink arrow indicator and tooltip with link source.

See #96603 (review)

[passivestar]

Idea for another PR: Create symlinks instead of copying if you hold Alt+Ctrl/Cmd when dropping files onto the dock

[bruvzg]

Idea for another PR: Create symlinks instead of copying if you hold Alt+Ctrl/Cmd when dropping files onto the dock

Won't work on Windows, making symlinks still require admin permissions (or enabled developer mode).

[akien-mga]

Thanks!

[Hilderin]

I have some concerns about this PR because it adds a check directly on disk for each directory and file everytime the FileSystemDock tree is recreated which is quite often. That will slow down considerably the tree update with large projects. It's already very slow for project with couple of thousand file (like 2-5sec). With a roundtrip to the disk, that will probably be catastrophic. In my opinion, the link information should have been added in the EditorFileSystem file tree and read while scanning and updated based on the last modified time like the other path and file properties. I did not do testing to prove my concern. I'll be glad to test it further and implement it if you wish.

[akien-mga]

Yeah that's a very good point, would be worth testing further to confirm the performance impact and how to improve it.