Keys.1.2: Add key

Adds a new key based on given type. A key can be a:

• Custom Key
• Project Key
• Teacher Key
• Student Key

The ACL of a block, key pod and block pod is driven by the type of key.

• A block, key pod or block pod in a custom key has to be individually shared with collaborators.
• A block in a teacher or project key can be shared with a collaborator, and all block pods inherit the ACL from the block. Key pods cannot be created in these keys.
• When a block in a teacher key is shared with a student (by granting them read access), it will appear in a student key of that student.