Add support for 'buf format'

[amckinney]

Now that buf format is released, we need to integrate it here.

[haunt98]

In latest version, vscode-buf auto format my .proto files. Is there any config to disable that.

[rubensf]

Forgot to tag this is as fixed by #70.

@haunt98 see this stackoverflow response: https://stackoverflow.com/questions/61827206/vscode-disable-all-auto-formatting-on-save#:~:text=Use%20vs%2Dcode%20default%20shortcut,search%20for%20save%20without%20formatting.

TL;DR: you can add this to your settings:

    "[proto]": {
        "editor.formatOnSave": false
    }