Add length validation to route name

[geezyx]

Description of changes:

According to the API reference, the route name must be at least 1 character and at most 255 characters. https://docs.aws.amazon.com/app-mesh/latest/APIReference/API_RouteData.html

Currently an empty string is valid input for the CRD, which results in an API error during reconcile. This can be caught early with a validation rule.

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[ysdongAmazon]

Thank you, Mike for pointing out. Executed unit tests