Add support for Goto Implementation

[thekalinga]

In vscode we have an action that lets us navigate to implementation. Looks like it is mapped to Ctrl+F12 by default. This should be mapped to Ctrl+Alt+B

Here is the default shortcut snippet I copied from vscode

{
  "command": "editor.action.goToImplementation",
  "key": "ctrl+f12",
  "when": "editorHasImplementationProvider && editorTextFocus && !isInEmbeddedEditor"
}