refactor: unify job spec repository

[irainia]

This is to address this issue. Changes:

• remove ProjectJobSpecRepository and NamespaceJobSpecRepository
• refactor job spec repository to handle job spec only
• remove ResolveStaticDependencies because:
  • error in its implementation caused by unification
  • fixing it is not done since this implementation is not used anymore
• update mock for plugin and job spec repository

Note: further detail could be added later

[coveralls]

Pull Request Test Coverage Report for Build 3157272229

• 68 of 217 (31.34%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-13.8%) to 63.938%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/store/postgres/adapter.go	0	6	0.0%
internal/store/postgres/job_source_repository.go	0	6	0.0%
internal/store/postgres/job_spec_repository.go	0	137	0.0%
<!--	Total:	68	217

Totals
Change from base Build 3133499995:	-13.8%
Covered Lines:	7904
Relevant Lines:	12362

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💛 - Coveralls

[sravankorumilli]

@irainia as discussed lets go through the key flows of all the repository interface methods once together with @arinda-arif