Make ChangeProposal Space scoped

[MaloPromyze]

• create the AbstractSpaceScopedRepository that mirrors the AbstractOrganizationScopedRepository
• add space to ChangeProposal entity & schema
• update change proposal repository to use AbstractSpaceScopedRepository
• update change proposal services & usecases to matches AbstractSpaceScopedRepository constraints
• remove cache repository

[cteyton]

Few findings in ChangeProposalDatabaseRepository.ts, in case they are relevant:

• findByArtefactId is not space-scoped, it returns proposals for an artefact across ALL spaces
• findBySpaceId doesn't use createScopedQueryBuilder - it seems to bypass the scoped pattern
• the method createScopedQueryBuilder in SpaceScopedRepository does not seem to be used