Migrate shared services and models in flagsmith-common

### Is your feature request related to a problem?

Several models, and services are used across different flagsmith repositories (`flagsmith-workflows`, `flagsmith-api`, `flagsmith-common`).
Migrating them to common would allow to reduce the repetition of logic and would provide more flexibility.

Candidates for migrations:
- `MetadataField`
- `MetadataModelField`
- `MetadataModelFieldRequirement`
- `SegmentCloneService`
- `ChangeRequestCommitService`
- `Project`
- `Segment`
- `SoftDeleteExportableModel`
- `SegmentRule`
- `Rule`

### Describe the solution you'd like.

Migrating them to flagsmith-common and re-use them in dependent repositories

### Describe alternatives you've considered

N/A

### Additional context

_No response_