Update gist in GitHub when user press a keybind / save

[barraIhsan]

Is your feature request related to a problem? Please describe.
So I realize when I use an autosave (afterDelay), its keep updating to Github. Sending request every second (depends on your delay). And then, I realize I hit the rate limit of the gistpad API. And I can't update anymore at that time.

Describe the solution you'd like
So like vscode formatter, Maybe just update it when the user actually save it (like ctrl s) or add a command, and attach a keybind for it (just like format document) instead of check if it saves or not

[lostintangent]

Closing this as a duplicate of #276. We'll introduce a seperate save behavior from VS Code, to provide the user with more control. Thanks!