[META] Garbage Collection Enhancement/Rework

Tracking for multiple GC related issues and enhancement proposals.

Currently Open Issues:
- #7784 GC strategy for public DSNlink gateways
- #4382 No GC
- #6381 GC basically useless for now
- #6114 Garbage Collection enhancements (prevent GC from locking repo)
- #3679 better gc
- #3092 More intelligent blockstore garbage collection

Historical Info; Closed Issues.
- #7213 IPFS Repo GC Is Unrealistic At Non-Trivial Scale
- #6322 `ipfs repo gc` very slow

Comments about current GC implementation: https://github.com/ipfs/go-ipfs/pull/1420
Enhancement effort: https://github.com/ipfs/go-ipfs/pull/4149

Block cache issues that may be pulled into GC work if block cache is also used for GC:
- #6934 Block cache lock contention
- [Optimize the has cache](https://github.com/ipfs/go-ipfs-blockstore/issues/3)