feat(cli): add models option in discover cli command to generate spec…

[sohaibahsan007]

added --models option inside lb4 discover the command to generate specific models

Fixes #7104

Checklist

• [x] DCO (Developer Certificate of Origin) signed in all commits
• [x] npm test passes on your machine
• [x] New tests added or existing tests modified to cover all changes
• [x] Code conforms with the style guide
• [x] API Documentation in code was updated
• [x] Documentation in /docs/site was updated
• [x] Affected artifact templates in packages/cli were updated
• [x] Affected example projects in examples/* were updated

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[coveralls]

Pull Request Test Coverage Report for Build 2340528877

• 8 of 8 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.007%) to 76.515%

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Totals
Change from base Build 2340239535:	0.007%
Covered Lines:	18022
Relevant Lines:	19119

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💛 - Coveralls

[sohaibahsan007]

@achrinza done. please review

[achrinza]

Please fix failing test.

[cloud20x]

@achrinza: may we please ask you to having a quick look at this PR? there is an error in the build, but no error message available. Thanks for the clarification...

[cloud20x]

@achrinza May I please ask you to get back to our question? And please add: [email protected] to this PR so he can take it forward? Thanks

[aaqilniz]

There hasn't been any progress from the PR creator. Can I recreate the PR referencing this PR to have this PR move forward? Or the PR can be merged without their response? @achrinza

[dhmlau]

Closing in favor of https://github.com/loopbackio/loopback-next/pull/9092