Stop button, context menu are not available if exp is running

[shcheklein]

If run it from a Terminal window with dvc exp run, I don't see a stop button. Also I can access the context menu, command palette is not available either (is it available at all?)

Extension version: v0.2.22

[mattseddon]

We currently (try) to suppress all experiment commands when an experiment is running because they will fail due to a repo lock and/or give unexpected behaviour.

For everything in the extension this is based on the dvc.runner.running context which is dependant on the experiment being run through the runner. This is the bug and why the run buttons are still shown instead of the stop button.

For the webview we use the exp show data to suppress the context menu.

We can update so that both the exp show data and the runner contribute to the context value.