Add support for merge incremental strategy

[cheyney-w]

Now that MERGE statements are supported in Fabric warehouses, it would be great if dbt-fabri` supported the merge incremental strategy.

[Germain-D]

#325

[pradeepsrikakolapu]

@Germain-D, @cheyney-w , PR #328 address to support merge.

@Germain-D , I could not merge your changes in for some reason. I will include you as an author in the release. So sorry for not able to pull your changes in.