Kotlin SDK schemas

### Describe the problem

https://github.com/WeblateOrg/weblate_schemas/ introduced support for Kotlin SDK, the schema is not yet finalized, but once it will be it should live in https://github.com/WeblateOrg/weblate_schemas/

### Solution brainstorm

Add schema to https://github.com/WeblateOrg/weblate_schemas/ and validate against it.

### Describe alternatives you have considered

_No response_

### Screenshots

_No response_

### Additional context

_No response_

Start by checking the Kotlin SDK support in the linked weblate_schemas repository and confirm when its schema is finalized. Then locate Weblate's existing schema validation flow; done means the finalized Kotlin schema is added in the appropriate repository and Weblate validates against it.

Written by the indexing model from the issue text.