feat: use constants for disposition

[SpencerC]

Fixes

Type checks arguments to SetDisposition, ensuring that the arguments are correct on the client side and developers don’t need to wait until runtime to see spelling mistakes.

Checklist

• I acknowledge that all my contributions will be made under the project's license
• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the Contribution Guidelines and my PR follows them
• I have titled the PR appropriately
• I have updated my branch with the main branch
• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary documentation about the functionality in the appropriate .md file
• I have added inline documentation to the code I modified

If you have questions, please file a support ticket.

[SpencerC]

@tiwarishubham635 @sbansla LMK if this is something you'd consider or not. If not, would love to close and get off my list.