[Deprecation] `GenesisConfig` -> `RuntimeGenesisConfig`

[kianenigma]

We renamed many of the composite enums such that the outer one is called RuntimeXXX eg paritytech/substrate#11981, but we seem to have missed this one.

Like other deprecations, we should keep the old name, but mark its usage is deprecated eg #182

### Deprecation steps
- [x] Soft deprecation and removal from the codebase https://github.com/paritytech/substrate/pull/14210
- [x] Update examples and tutorials https://github.com/substrate-developer-hub/substrate-docs/issues/1996
- [x] Hard deprecation by adding a deprecate compiler warning https://github.com/paritytech/substrate/pull/14224
- [x] Deprecation is noted in the release log
- [x] Removal version is planned -> after 16 Dec
- [ ] Deprecated feature is removed from the code base
- [ ] Removal of the feature is noted in the release log