Update Neptune Engine Version or add it as part of prompts

[joysl]

Aws Connected Device Framework Affected Module(s):

I'm submitting a ...

• bug report
• feature request

Description:

Current behavior:

Expected behavior:

Steps to reproduce:

Additional Information:

[joysl]

CDF deploys a Neptune DB based on the instance family as part of the AWS::Neptune::DBClusterParameterGroup but there's no EngineVersion available to specify the available patches beyond minor version.

[joysl]

#179