[ServerlessVpcConnection] Add schema

[lastrell]

Issue #, if available:

Description of changes:

Adding the serverless vpc connection resource schema for CFN support. All the other stuff was generated by cfn-init. The main focus is to get schema completed before working on the handlers so that AppSec review can happen in parallel w/ handler development.

Steps taken in this PR:

Create directory aws-msk-serverlessvpcconnection
cd into directory
Run cfn-init
Type r in the prompt
Type AWS::MSK::ServerlessVpcConnection
Select guided-aws as the codegen model
Modify the JSON file

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