Split out core functionality of `random` into new `random-core` package

As it was discussed in https://github.com/haskell/random/issues/156#issuecomment-1889812810 and https://github.com/haskell/random/issues/156#issuecomment-1889868874 we should split out the core functionality of `random` out into a new `random-core` package, which would be the direct dependency of QuickCheck, thus allowing for easy testing of boot packages like `bytestring` without creating circular dependencies.

This would allow us to not only provide `Uniform` and `UniformRange` instances for more types from boot libraries, but would allow us to expend the interface to generating random data structures (eg, `containers`, `array`, etc.)

Start by reading the linked discussion in issue 156 to understand the proposed package boundary and dependency constraints. Identify the core functionality to move from random into random-core, then verify that QuickCheck can depend on it directly and that the package supports the intended boot-library instances and future data-structure generators.

Written by the indexing model from the issue text.