Update folder details outside of `Run`

[kzscisoft]

Currently you can only set folder details using a new run which is a problem if the user wants to just update the details outside of creating runs.

• Create a folder details modification function in Client.
• Consider if Run.set_folder_details should always apply to the folder associated with the current run (makes sense), hence remove path argument.

[kzscisoft]

With this MR the equivalent is now:

folder: Folder = client.get_folder(folder_path="/my/folder", read_only=False)
folder.description = "Test folder"
folder.commit()