feat: Add CFT test lint subcommand, implement blueprint connection source version lint rule for POC

[qz267]

This PR implemented go/blueprint-metadata-lint, implement a POC rule to verify the version value in ConnectionSource, valid version values including:

• "=1.0.0"
• ">=2.0.0"
• ">=3.0.0 <5.0.0"
• "~>4.0"

[qz267]

a sample metadata lint output is:

-> % ~/src/cloud-foundation-toolkit/cli/bin/cft test lint
metadata, spec, or interfaces are nil
All lint checks passed!
zhengqin@yard [11:47:55 PM] [~/src/cloud-foundation-toolkit/cli/testdata/bpmetadata/content/examples/acm] [367401040-lint-ADC]
-> % ```

[bharathkkb]

Looks great @qz267

[qz267]

@bharathkkb all comments addressed, will update design doc accordingly