feat: add additional webhook params

[Justintime50]

Description

To the next dev that picks this up, we need to:

1. Add the custom_headers to the create and update parameter sets
2. Ensure that the update webhook overload function that uses the param sets doesn't need to have the params wrapped for it to work as expected
3. Update create/update webhook tests to pass in the webhook_secret and custom_headers to ensure we pass them correctly

Testing

Pull Request Type

Please select the option(s) that are relevant to this PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement (fixing a typo, updating readme, renaming a variable name, etc)