[FEATURE] Extended product repository and manager for fetching master product

Extended product repository and manager for fetching master product

__Tasks:__

- [x] added new function for fetching master (product with variants) product
- [ ] gather feedback for my changes



__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none
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