Provide "refresh all" type operation

I am not sure where (or how many levels) in this stack need to be addressed for this.

Right now if something in the UI becomes out of sync with gdb, there isn't really a way to recover. Users can do continue/pause in the CLI and that may return the UI to the correct state. In CDT we have a "refresh all" command that tells the client/adapter (or their Eclipse equivalents) to re-fetch all state from gdb.

In practice this out of sync doesn't happen often, but sometimes when threads start/stop quickly the overall state can become incorrect.