feature(sms): Added incoming signature verification

[dragonmantank]

Description

Adds incoming signature verification to the SMS module. This adds a new verifySignature() method to the SMS module where the user can pass in the incoming signature, parameters to check, their signature secret, and the configured algorithm type.

Motivation and Context

Customer expectations dictated that we added this back into the SDKs. To avoid issues with JWT verification, this is added directly to the SMS API as it is the only one to use this verification technique.

Testing Details

Unit tests ported from the PHP testing suite.

Example Output or Screenshots (if appropriate)

Types of changes

• 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 read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.