Also this now tests all sub-crates and no longer only pdsl_core.

They are now a bit more aligned to what substrate generates for modules etc.

- They were no longer compiling since pdsl_core dependency got dropped.
- We now have better ways to test pdsl_lang.

This removes the critical dependency to pdsl_core.

This is important due to restrictions in Cargo dependency and crate feature resolving.
For example: We currently cannot link to pdsl_core from pdsl_lang since this would cause problems with duplicate panic handlers.
Having another minimally kept pdsl_utils we can use this to offload some common utility from pdsl_core into pdsl_utils to make them usable in pdsl_lang.

Now uses error facilities instead of simply panicking.