[keycloak-dev] A lot of unneeded files in themes common

[Stian Thorgersen]

I took a stab at cleaning up the node_modules (not for account2) by adding
a new profile to themes that can download packages from NPM. Then
copy/filter these to the directory used to build the server.

Benefits here:

* Removes unneeded files from dist
* Files included when running KeycloakServer is the same as in the dist
(filtered)
* All files/sources still checked in for RH-SSO
* Folks don't have to run this to build

You can try it out here:
https://github.com/stianst/keycloak/tree/KEYCLOAK-6378

cd themes
mvn -Pnpm-update clean install

Unless you change the package.json you shouldn't see any files to commit
afterwards. If you do there may be something with line encodings on Linux
vs Windows that we need to address (we should be able to tweak that by
adding a custom .gitattributes file in the node_modules dir).

Login, account and admin seems to work just fine with all these files
removed. There's probably more we can remove, but I think this is
sufficient at least for now.