fix(sequelize): extend Inclusion interface with "required" property

[KalleV]

Partial fix for: #10193

This resolves Typescript errors such as the following when trying to use the new property with a repository call using "find", "findOne", "findById":

Type '{ relation: string; scope: { where: { id: number; }; }; required: true; }'
is not assignable to type 'InclusionFilter'.
  Object literal may only specify known properties, and 'required'
does not exist in type 'Inclusion'.

53           required: true

Reference:
https://loopback.io/pages/en/lb4/readmes/loopback-next/extensions/sequelize/

Checklist

• DCO (Developer Certificate of Origin) signed in all commits
• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• API Documentation in code was updated
• Documentation in /docs/site was updated
• 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 6983324259

Warning: This coverage report may be inaccurate.

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A quick fix for this PR: rebase it; your next report should be accurate.

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 110 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-0.007%) to 57.036%

---

Files with Coverage Reduction	New Missed Lines	%
packages/repository/src/relations/belongs-to/belongs-to.repository.ts	6	48.94%
packages/repository/src/relations/has-one/has-one.inclusion-resolver.ts	9	55.26%
packages/repository/src/relations/has-one/has-one.repository.ts	22	24.65%
packages/repository/src/relations/has-many/has-many-through.repository.ts	73	0.61%

Totals
Change from base Build 6886297667:	-0.007%
Covered Lines:	9563
Relevant Lines:	12457

---

💛 - Coveralls

[shubhamp-sf]

Why does it need to affect the types of core repository module, instead of type extension in the Sequelize repository itself. For the respective methods (find(), findOne(), and findById()).

I'm not certain about the behaviour this code will have but It can reflect to non sequelize repositories as well, which might not be intended here.

[KalleV]

@shubhamp-sf Thanks for reviewing this. Yes, the TS declaration merging approach affects non-sequelize repositories too. Extending the method interfaces is much better, however, it doesn't cover the relation query "find" case like:

myRepository(foreignKey).find({
  include: [
    {
      // ...
      required: true
    }
  ]
}

I tried a couple of approaches for that case. Perhaps defining new interfaces like "SequelizeHasManyRepositoryFactory" that extend the find method in the underlying interfaces such as HasManyRepository?

[shubhamp-sf]

LGTM

[dhmlau]

@shubhamp-sf, I'm merging this PR based on your approval as you're the code owner.

[dhmlau]

@KalleV, thanks for your contribution. Your PR has landed! 🎉