[VSCODE] Add a snippet or command to add link and script tags to index pages for manifest and service worker

[nmetulev]

Tell us about your feature idea

Generating a manifest or a service worker also requires updating the head of the index page. The service worker generation attempts to do this automatically but it doesn't always work depending on the framework or setup of the project. The vscode extension should have snippets or commands to insert the link or script tag at the current open file.

Do you have an implementation or a solution in mind?

A simple snippet should work

Have you considered any alternatives?

No

[jgw96]

Fixed with above PR