Change the behavior of lb4 CLI

[hacksparrow]

The fact that lb4 scaffolds a REST app by default implies LoopBack 4 (lb4) is a REST framework, when it is not. Users now assume LB4 is a REST framework and go to the website expecting to find the docs of a REST framework, instead they find the documentation of a super-framework.

We should start using --rest for scaffolding REST apps, --graphql for GraphQL app, --grpc for gRPC app etc.

If one has to do lb4 --rest, they will naturally be curious, "Why do we have to add --rest", "What else is there?", "I needed a gRPC app, can LB4 do it?", etc. This sets a better context about what LB4 really is.

I brought it up on #5551 and repeat it again, our documentation problem is more of an identity problem than organization problem; the docs re-organization exercise can fix it only to a certain extent. Unless we decide on a clear cut identity of LB4 and back it up with docs and tooling, the core of the problem will still remain.

Acceptance Criteria

• lb4 should print help message.
• lb4 --rest [name] should scaffold a REST app with the optional name parameter.

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[stale]

This issue has been closed due to continued inactivity. Thank you for your understanding. If you believe this to be in error, please contact one of the code owners, listed in the CODEOWNERS file at the top-level of this repository.