op-challenger: cleanup service lifecycle, improve subscription ctx usage

[protolambda]

Description

Clean up the challenger service lifecycle:

• register interrupt signal handling immediately at main, and attach it as value to ctx, for the app lifecycle to utilize
• turn game.Service into a service with a lifecycle; explicit Start / Stop methods.
• Make the game.Service close all its initialized resources.
• Use the same pattern as batcher/proposer/op-node/indexer: init from config, and if there's an error during initialization, try to close what's left open of the service.
• Now that the challenger has a lifecycle, the test Helper doesn't need to maintain a channel and context, and can just stop the challenger.

Improve related op-service utils:

• improve WatchHeadChanges: unsubscribe signals are now handled in parallel to the subscription tasks, and cancel the context internally. This way an "unsubscribe" really is an unsubscribe, and we don't also have to keep track of a long-running context that has to be closed prior to unsubscribing. The ctx attribute is only used for the duration of the call that creates the subscription, and does not affect the subscription after that.
• similarly, fix PollBlockChanges to also handle unsubscribe signals like that
• add a Close() method to the simple tx-manager, so services can shut down the underlying RPC client connection.

With the above op-service fixes:

• Also close the subscriptions in op-node properly, don't use the resource ctx for
• Close the tx-manager in op-proposer and op-batcher

Tests

No functionality changes, just cleanup. Open for suggestions to add tests where previously missing.

Metadata

Part of #7671

[ajsutton]

LGTM. Really nice clean up.

[codecov]

Codecov Report

Merging #8235 (1e157a7) into develop (2e35a8f) will increase coverage by 7.81%.
Report is 24 commits behind head on develop.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8235      +/-   ##
===========================================
+ Coverage    53.44%   61.26%   +7.81%     
===========================================
  Files          162       86      -76     
  Lines         6040     1931    -4109     
  Branches       964      438     -526     
===========================================
- Hits          3228     1183    -2045     
+ Misses        2690      672    -2018     
+ Partials       122       76      -46     

Flag	Coverage Δ
cannon-go-tests	?
chain-mon-tests	?
common-ts-tests	?
contracts-bedrock-tests	61.26% <ø> (ø)
contracts-ts-tests	?
core-utils-tests	?
sdk-next-tests	?
sdk-tests	?

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see 76 files with indirect coverage changes

[ajsutton]

I suspect the flaky test from the merge queue failure will be fixed by #8217