Toggleable sprinting and crouching

Add support for configurable toggle modes for sprinting/running and crouching.

Expected behavior:
- Player movement should expose a run toggle mode setting with Off, Permanent, and UntilNoInput options.
- Player movement should expose a crouch toggle mode setting with Off and Permanent options.
- The new settings should be writable and readable from the PlayerMovement API so projects can configure whether run/crouch require held input or toggle behavior.

Constraints:
- Do not modify tests.
- Do not create helper scripts or extra files.
- Make the smallest production code change needed.

Repository context:
- Base commit: 10c6b8001c54faf561156d7ce819924f7925300a
- Unity version: 2018.3.3f1
- Main production file: Assets/Hertzole/Gold Player/Scripts/Core/Modules/PlayerMovement.cs
- Supporting enum file: Assets/Hertzole/Gold Player/Scripts/Core/Data Types/Enums.cs

--- Original GitHub issue (auto-fetched) ---
Title: Toggleable sprinting and crouching

Body:
Have the ability to toggle sprinting and crouching.
