Add button into "Run and Debug" tab

[Quatters]

For users who actively using mouse this would be useful. The button should launch currently selected config. Also, ability to show/hide it in settings would be great.

[Quatters]

There are two troubles:

1. It's impossible to add additional buttons into "Run and Debug" title.
2. There is no API for writing currently selected config (ability to get/set currently selected debug configuration microsoft/vscode#77138).

However, first can be solved by adding buttons to editor title. Second can partially be solved by listening for onDidTerminateDebugSession and saving launched configuration in extension's context (but I still cannot force regular Start Debugging command to use the configuration launched by previous execution of Select and Run Without Debug).

Will try this approach in the next release.