Add the support for multiple plugins inside a single Gradle project

[ivandev0]

I would like to have a single Gradle project with the following structure

- shared    <--|
- plugin1    --|
- plugin2    --|

Here plugin1 and plugin2 depend on the shared module. I can build and publish each plugin separatly as completely different plugins. I would guess that this can be easily done with Gradle subprojects, but it is quite hard to do a proper setup. If this is already implemented, it would be nice to have an instruction in the documantation.