batcher refactor: flatten out go routines

[geoknee]

This is a refactor to try and make the two three goroutines spawned by the driver equally clear.

• Names the previously anonymous receiptsLoop This got done already while this PR was open.
• Adds some godoc comments about what each loop does
• Tries to be a little more idiomatic about passing contexts in to functions

[semgrep-app]

Semgrep found 1 err-todo finding:

• op-program/client/l2/engineapi/l2_engine_api.go
  • L500 - Triage

TODO in error handling code

_{Ignore this finding from err-todo.}

[semgrep-app]

Semgrep found 3 sol-style-require-reason findings:

• packages/contracts-bedrock/scripts/deploy/Deploy.s.sol
  • L1002 - Triage
  • L1083 - Triage
  • L1090-1093 - Triage

require() must include a reason string

_{Ignore this finding from sol-style-require-reason.}

Semgrep found 6 sol-style-input-arg-fmt findings:

• packages/contracts-bedrock/src/L2/interfaces/ISuperchainWETH.sol
  • L20 - Triage
  • L25 - Triage
  • L26 - Triage
  • L29 - Triage
  • L30 - Triage
  • L32 - Triage

Inputs to functions must be prepended with an underscore (_)

_{Ignore this finding from sol-style-input-arg-fmt.}

Semgrep found 4 golang_fmt_errorf_no_params findings:

• op-supervisor/supervisor/backend/db/db_test.go
  • L280 - Triage
• op-chain-ops/deployer/state/intent.go
  • L75 - Triage
  • L83 - Triage
• op-chain-ops/deployer/bootstrap/bootstrap.go
  • L59 - Triage

No fmt.Errorf invocations without fmt arguments allowed

_{Ignore this finding from golang_fmt_errorf_no_params.}

Semgrep found 1 math-random-used finding:

• op-supervisor/supervisor/backend/source/head_monitor_test.go
  • L7 - Triage

Do not use math/rand. Use crypto/rand instead.

_{Ignore this finding from math-random-used.}

Semgrep found 1 marshal-json-pointer-receiver finding:

• op-supervisor/supervisor/backend/db/heads/types.go
  • L99 - Triage

MarshalJSON with a pointer receiver has surprising results: golang/go#22967

_{Ignore this finding from marshal-json-pointer-receiver.}

Semgrep found 1 err-nil-check finding:

• op-supervisor/supervisor/backend/db/db.go
  • L108-112 - Triage

superfluous nil err check before return

_{Ignore this finding from err-nil-check.}

[vdamle]

lgtm!

[tynes]

This looks like it needs a rebase now before we can merge it

[geoknee]

This looks like it needs a rebase now before we can merge it

Yes, I'll do that now.