deposits/schemas: validate data without saving to db

[pamfilos]

Feature request

What is the expected behavior? Create API endpoints e.g

• [x] for /deposits/<id>/actions/validation
• [x] for /schema/<schema_name[/schema_version]/validate

that will receive data (item OR list) from the request and validate data against schema/deposit_schema

What is motivation or use case for adding/changing the behavior? To be able to test data before sending for update

[ParthS007]

Breaking out the tasks in steps:

1. Create a endpoint in schema module to have basic schema validation (DRAFT4Validator)
2. Replicate the deposit creation just before the deposit getting saved into db.
3. Create a action for validation of schema in deposits module.

[ParthS007]

The deposit creation does following checks:

1. User Authentication Check
2. Metadata check (schema/ana_type)
3. JSONschema validation (modifying and permission control)
4. Indexing ..