| Elektra 0.11.0

Use Case: `Key` lock

# Summary

- Scope: `libelektra-core`
- Level: Developer Goal
- Actors: Core, Caller
- Brief: Access to and manipulation of `Key`'s lock flags
- Status: Implemented

# Scenarios

- Precondition:
  - `Key` has been created
- Main success scenario:
  - Caller requests lock status of one or multiple flags of a `Key`
  - Possible lock flags are: name, value, metadata
  - Core returns for which lock flags the lock bit is set in the `Key`
- Alternative scenario:
  - Caller requests to set one or multiple lock flags for `Key`
  - Possible lock flags are: Name, Value, Meta
  - Core sets bits for lock flags in the `Key`
- Error scenario:
- Postcondition:
  - Locked fields cannot be changed via other functions from the Elektra Core API
- Non-functional Constraints: