feat: allow empty array in createAll method

[ajay-prajapati07]

Added code to allow empty array in createAll method. Currently it throws error.

Include references to all related GitHub issues and other pull requests, for example:

Fixes #2409 -->

Checklist

• [ ] Sign off your commits with DCO (Developer Certificate of Origin)
• [ ] 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

[samarpanB]

Also please sign off your commit. Follow DCO here - https://loopback.io/doc/en/contrib/code-contrib.html

[coveralls]

Pull Request Test Coverage Report for Build 15629436334

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 2 of 10 (20.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 84.647%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/dao.js	2	10	20.0%
<!--	Total:	2	10

Totals
Change from base Build 15670951978:	-0.06%
Covered Lines:	7279
Relevant Lines:	8293

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💛 - Coveralls

[samarpanB]

Can you please add a test case for this option ?