polkadot-node-subsystems: `ChainApiBackend` added + `polkadot-debug` image version fixed (#2411)

The out-dated version (bad tag) of [polkadot
image](https://github.com/paritytech/polkadot-sdk/blob/ede4a362622dfa69eb167eaa876246b1289f4b41/.gitlab/pipeline/zombienet/cumulus.yml#L31)
([docker
info](https://hub.docker.com/layers/paritypr/polkadot-debug/master/images/sha256:adb1658052cf671b50c90d5cece5c7a131efa1a95978249bd5cb85a5ad654f7a?context=explore))
was used. This PR fixes this.

See also:
https://github.com/paritytech/polkadot-sdk/pull/2411#issuecomment-1822632724



Also adds an abstraction that allows asynchronous backends to be passed to `ChainApiSubsystem`
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Co-authored-by: Sebastian Kunert <[email protected]>