Invocation name requirements

[KristaTheCoder]

Proposed changes

Added validation for Amazon Alexa Invocation Name requirements

Previous:
-- Checked Undefined or Empty Invocation name

Added:
-- Checks for length requirement
-- Checks for lower case letter requirement
-- Checks no numbers requirement

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 added tests to cover my changes
• All new and existing tests passed

(I'm not sure how to write tests for this feature & latest commit doesn't show any errors as far as I know)

[jankoenig]

Thanks a lot @KristaTheCoder 👍 We'll take a look

[aswetlow]

Thanks @KristaTheCoder !