feat(contracts): `PluginRepo` refactor part II

[josemarinas]

Description

• [x] contains many external functions that are not part of IPluginRepo
• [x] being able to specify an initialVersion making

Task ID: OS-1330

Type of change

See the framework lifecycle in packages/contracts/docs/framework-lifecycle to decide what kind of change this pull request is.

• [x] New feature (non-breaking change which adds functionality)

Checklist:

• [x] I have selected the correct base branch.
• [x] I have performed a self-review of my own code.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [x] My changes generate no new warnings.
• [ ] Any dependent changes have been merged and published in downstream modules.
• [ ] I ran all tests with success and extended them if necessary.
• [ ] I have updated the CHANGELOG.md file in the root folder.
• [ ] I have updated the DEPLOYMENT_CHECKLIST file in the root folder.
• [ ] I have updated the UPDATE_CHECKLIST file in the root folder.
• [ ] I have updated the Subgraph and added a QA URL to the description of this PR.