Added withSkipDuplicates import concern

[frknakk]

1️⃣ Why should it be added? What are the benefits of this change?
Allow skipping duplicate rows on single and batch inserts using insertOrIgnore method. Good for use cases where files could be imported multiple times and only a simple duplicate check is needed. In my project i had some quality and performance issues when using upsert for this use case.

2️⃣ Does it contain multiple, unrelated changes? Please separate the PRs out.
No

3️⃣ Does it include tests, if possible?
Yes

4️⃣ Any drawbacks? Possible breaking changes?
No

5️⃣ Mark the following tasks as done:

• Checked the codebase to ensure that your feature doesn't already exist.
• Take note of the contributing guidelines.
• Checked the pull requests to ensure that another person hasn't already submitted a fix.
• Added tests to ensure against regression.