fix: return inserted ids with models in createAll

[samarpanB]

Signed-off-by: Samarpan Bhattacharya this.is.samy@gmail.com

Fixes an issue with newly introduced createAll() method where it was not returning all ids of inserted records. The format of the data returned was also wrong. Introduced a new base function getInsertedIds() which needs to be implemented by connectors if they use multi insert support. It is similar to getInsertedId().

See also #227 and loopbackio/loopback-next#3357

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
• Commit messages are following our guidelines

[coveralls]

Pull Request Test Coverage Report for Build 3401100679

• 1 of 10 (10.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.2%) to 58.264%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/sql.js	1	10	10.0%

Totals
Change from base Build 3398161402:	-0.2%
Covered Lines:	694
Relevant Lines:	1127

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 3401100679

• 1 of 10 (10.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.2%) to 58.264%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/sql.js	1	10	10.0%

Totals
Change from base Build 3398161402:	-0.2%
Covered Lines:	694
Relevant Lines:	1127

---

💛 - Coveralls

[dhmlau]

@samarpanB, thanks for your contribution. Your PR has been merged! 🎉