feat: support non-primary reference keys of source and target model for hasManyThrough relation

[aaqilniz]

This PR will provide support for non-primary key references of source & target models in case of hasManyThrough relation.

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
• [ ] API Documentation in code was updated
• [x] Documentation in /docs/site was updated
• [x] Affected artifact templates in packages/cli were updated
• [ ] Affected example projects in examples/* were updated

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[coveralls]

Pull Request Test Coverage Report for Build 7687463955

• -4 of 4 (0.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.03%) to 55.344%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/repository/src/relations/has-many/has-many-through.helpers.ts	0	4	0.0%
<!--	Total:	0	4

Files with Coverage Reduction	New Missed Lines	%
packages/repository/src/relations/has-many/has-many-through.helpers.ts	1	7.59%
<!--	Total:	1

Totals
Change from base Build 7663796800:	-0.03%
Covered Lines:	9563
Relevant Lines:	12459

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💛 - Coveralls

[aaqilniz]

Hi, @samarpanB. Can you please have look at this PR?

[samarpanB]

Can you share an example where this might be useful ? I believe hasManyThrough need to be mostly with primary keys only.

[aaqilniz]

@samarpanB. We can create hasManyThrough (or any other relation) with a unique key - which can be a non-primary key.