feat: pre Astroport v6 cleanup

[epanchee]

Collecting breaking changes for upcoming Astroport v6 release

1. Removed customized cw20 contract with balance tracking. Used as xASTRO contract on Terra and as LP token with balance tracking on Neutron. Both these use cases are not relevant anymore;
2. Removed restricted_vector type which is legacy type from old Astro Generator contract;
3. Removed observation logic and circular buffer. This approach didn't find any use especially because it was simple moving average over 3000 last trades (without any relation to time);
4. Removed Vesting contract which served as centralized place for Astro emission schedules. After vxASTRO launch all emissions are paid out as external rewards which renders this contract irrelevant;
5. Removed Fee Granter contract which was part of initial design for Injective orderbook integration via begin blocker.