Add support for Nrwl/NX

[adover]

In my company we use NX Monorepos to house our applications and our design system. I would like to make some modifications to Keycloakify to allow us to be able to do the following:

• Specify NX as a build provider, either detected automatically or by an argument in the command line
• With NX as the build provider, paths for build and build_keycloak are modified to be inside the dist folder
• The keycloakify project is resolved dynamically somehow

I plan to raise a PR for this, but open to suggestions from the community!