Move examples to in-repo non-submodule folder

The current example* submodules have a couple of shortcomings that would be nice to address:
- they are part of the project build
- so they are released (unnecessarily)
- do not fully document library usage (just import the module, not the built jar)
- currently are not runnable on their own, just as part of the testing runners (this can be leveraged by providing the provided dependencies or compiling those in, also they depend on scala tests, etc.)

Let's take inspiration in [Cobrix](https://github.com/AbsaOSS/cobrix/tree/master/examples). The example apps each have their own `pom.xml`, so they are not part of the build, but they are build-dependent on the main library compatible version.

This way, we can achieve the following:
- clean up the normal build and release
- still have examples as part of the codebase
- have the example apps runnable (via test runners, possibly on its own - optional)