Remove the feature of "v.vls.restart"

[felixf4xu]

Hi,

The feature of restarting vls from vscode extension might have history reasons, but it has not done it right.

In current implementation, to restart the vls server child process, the client process is also killed (actually it does not work). This is not an extension should do. If the user want to restart both language server and client, it's better just to disable and then enable the extension.

I would suggest to remove this feature because the design was not quite right and the implementation does not work.