refactor: Improve c8y_mapper_ext operation handler API #5900

Job	Run time
Block fixup commits	8s
Filter changes	3s
Check whether Cargo.lock is up to date	15s
Shellcheck	6s
Spell Check with Typos	5s
Sort dependencies	2m 2s
Run cargo fmt	14s
Run cargo audit	7s
Check for unused dependencies	6m 44s
Run cargo clippy	38s
nightly / doc	50s
Run cargo check on MSRV	37s
Run cargo test	6m 39s
Check markdown	0s
	18m 28s

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