Add helper function for matching CanFulfill Intent name

[timothyaaron]

Description

Provide matching helper function for IntentRequest-specific is_intent_name() to CanFulfillIntentRequest... for use in can_handle().

Motivation and Context

Follow DRY principles.
Simply intent matching.

i.e.,

return (
    is_request_type('CanFulfillIntentRequest')(handler_input) and
    handler_input.request_envelope.request.intent.name == 'MyIntent'
)

to...

return is_canfulfill_intent_name('MyIntent')(handler_input)

Testing

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 README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.