mgr/dashboard: Add reload button for CephFS directories
As many request have to made in oder to reload the all directories, the requests are only done once.
This isn't as intuitive as most pages use the build in auto reload feature of cd-table.
As this is a different structure it's a bit harder to update as there are two source that have to be updated.
There are 2 solutions two handle it:
1. Just replay all requests (will reload and therefore update all loaded directories)
2. Do one really big request with the deepest open depth (will load all available directories into this depth)