Republishing needed GrammarKit and IntelliJ dependencies as shadow Jar on MavenCentral

[hfhbd]

Is your feature request related to a problem? Please describe.
The code generation needs GrammarKit and some IntelliJ dependencies. These dependencies are only published on internal repos.
These repos are added by this plugin under the hood, if you don't use the new dependency resolution management #73 and #106.
If you use the new dependency resolution management, you have to add the IntelliJ repos too.

Describe the solution you'd like
Create a uber/fat/shadow jar containing all needed dependencies for the lexer and the parser and publish these dependencies at mavenCentral. Ideally, these dependencies are fine-tuned to only included needed deps, but no IntelliJ overhead (eg UI).

Describe alternatives you've considered
Keep the current state by also depending on the internal repos.

Additional context
We already did this in sqldelight, a sql compiler using the IntelliJ compiler apis, which makes the consumer usage way nicer: sqldelight/sqldelight#4079
Additionally, the Kotlin compiler uses this technique too, except it contains the shaded deps directly in the jar, this is the reason for the size of 56MB.

If you accept such change, I am open to create a PR.