add tunnel_protocol field to policy

[jlu-cloudflare]

Description

Adds a new tunnel_protocol field to the policy, which ultimately allows admins to switch tunnel protocols through their policy settings.

Has your change been tested?

Because it is just adding a new field to the various device settings policy structs, this should not affect existing uses of it. An existing test for the device policy fields has been updated to include the tunnel_protocol field to verify it's use.

Screenshots (if appropriate):

Types of changes

What sort of change does your code introduce/modify?

• 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 change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• This change is using publicly documented in cloudflare/api-schemas
  and relies on stable APIs.

[github-actions]

changelog detected ✅

[jacobbednarz]

lgtm once we have this in the API schemas 👍

[jacobbednarz]

saw this just landed. v2 has these changes at #2784.

[github-actions]

This functionality has been released in v0.101.0.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!