@sandy081 would be happy if you could check if the implementation makes sense

//cc @alexdima this adds the most basic atomic write to the file service (behind an option) which is:

• write to a file <resource path>.vsctmp in the same folder
• move the file to <resource path>
• skip our internal events and only send a single event (as we would have it without atomic writes)

Some notes:

• this will actually work with any file system provider because it leverages existing capabilities [1]
• some external file watchers maybe confused (I think thats ok, our watcher should be fine)
• when process dies, we risk to keep .vsctmp files laying around (I think thats ok too, because its never acumulating, its always the same tmp file)

[1] we could consider making this a capability and move this into the provider itself to do the write and move one after the other without going over processes, but I think it does not change the aspects of it much.