[Deprecation] deprecate `trait Store` in FRAME storage

[kianenigma]

... similar to #223, for now mark it as deprecated and remove all usage in Substrate.

### Deprecation steps
- [x] Soft deprecation and removal from the codebase paritytech/substrate#13535
- [ ] https://github.com/substrate-developer-hub/substrate-docs/issues/2020
- [x] Hard deprecation by adding a deprecate compiler warning paritytech/substrate#13535
- [x] ~Deprecation is noted in the release log~
- [x] Removal version is planned -> after Oct 1
- [ ] Deprecated feature is removed from the code base
- [ ] Removal of the feature is noted in the release log

[kianenigma]

This is done, in roughly 3 months, we will remove the code associated with it.