[keycloak-dev] Deploy theme as module and simplified creating theme for embedding

[Stian Thorgersen]

I've introduce the concept of a theme packaged as a JAR. This makes it possible to deploy a theme as a module (which is nice for domain mode) and simplifies creating themes when KC is embedded into other projects.

A theme JAR consists of:

* META-INF/keycloak-themes.json           A description of what themes are included in the jar
* theme/<theme type>/<theme name>         Templates, resources, etc as before

Basically there's no longer any need to implement your own theme provider just to bundle a theme as a jar :)

While doing this I realised that the structure of:

* <theme type>/<theme name>

Is wrong! It should be:

* <theme name>/<theme type>

Anyone have an objection to changing that? The reasoning is that it will be common to create a theme of different variants and having the theme name as the root makes it easier to copy to standalone/configuration/themes as well as groups everything for a theme into one place.