Implement `consistent-naming`

[illright]

Detect consistent naming of slices on layers (singular vs plural, casing)

• [x] Implement singular/plural consistency checks
• [ ] Add a special error for cases when an entity exists in both singular and plural (i.e. entities/product and entities/products at the same time)
• [ ] Implement singular/plural fixes
• [ ] Add support for multi-word slice names
• [ ] Implement case consistency checks and fixes