feat(internal/client): Introduction of Client that implements LockImportRun, BlockchainEvents, and PrecommitActions.

[timwu20]

Changes

• Introduction of BlockchainEvents interface.
• Introduction of PreCommitActions interface.
• Introduction of new Client type that implements both BlockchainEvents and PrecommitActions interfaces.
• Introduction of Client.LockImportRun function that will be used as a dependency in future work.
• Unpinning functionality and background goroutine within Client to unpin blocks from memory based on notifications
• Pubsub module utilized in sending out storage notifications from Client.

Tests

go test -tags integration github.com/ChainSafe/gossamer

Issues

closes #4455, #4456, #4457

[haikoschol]

just some typos & nits

[haikoschol]

Suggested change

	npw.pinnedBlocks.Add(hash, count)
	if count == 0 {
	npw.pinnedBlocks.Remove(hash)
	}
	if count == 0 {
	npw.pinnedBlocks.Remove(hash)
	} else {
	npw.pinnedBlocks.Add(hash, count)
	}

[timwu20]

Since pinnedBlocks is an lru cache this is expected behaviour. We should be modifying the count before we remove. See the substrate impl.

[haikoschol]

Why does this warrant a panic? I would have gone with a debug log (or maybe warning).

[timwu20]

I replicated this from the substrate impl. I think given this is an internal registry type, we want to alert the developer that this is wrong behaviour. We shouldn't be unregistering subscription IDs that do not exist.