New contextual links are not available after a module is installed

If a module defines a new contextual likes in a *.links.contextual.yml file they are not available unless 1 of these things happens:

1. The user's permissions change
2. The user opens a new browser session
3. The user logs out and in.

This is because the contextual links are cached on the client-side and the cache is not cleared unless the hash created by the user's permissions hash changes.

I found while working on #2753941: [Experimental] Create Outside In module MVP to provide block configuration in Off-Canvas tray and expand site edit mode which creates a new contextual link.

This could be fixed by a relying on a hash of current modules installed in addition to permissions.