feat: add service/repo interfaces for Plan API #5206

Job	Run time
Build	1m 22s
Commit hooks	49s
CI	5m 0s
Dependency review	4s
Developer environment	54s
E2E	6m 13s
FOSSA Scan	0s
Lint	3m 42s
Migration Checks	2m 38s
Quickstart	3m 57s
Test	4m 57s
Artifacts / Container image	2m 10s
Artifacts / Benthos Collector Container image	1m 53s
	33m 39s

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