Fix snapshot compilation error

[kingfink]

resolves #2787

Description

Implements strategy-specific validation for the timestamp and check strategies. As a result compilation errors are more relevant and clear to the user.

Checklist

• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have updated the CHANGELOG.md and added information about my change to the "dbt next" section.

[cla-bot]

Thanks for your pull request, and welcome to our community! We require contributors to sign our Contributor License Agreement and we don't seem to have your signature on file. Check out this article for more information on why we have a CLA.

In order for us to review and merge your code, please submit the Individual Contributor License Agreement form attached above above. If you have questions about the CLA, or if you believe you've received this message in error, don't hesitate to ping @drewbanin.

CLA has not been signed by users: @kingfink

[jtcohen6]

This looks great!

We could add a test for the repro case in #2787, but I don't feel so strongly about it—this doesn't represent a functional change, it just raises a more relevant error.

I see you added the changelog entries under v0.18.1. I think it's perfectly reasonable to get this in sooner rather than later; I'll change the base branch to match.

Edit: Since you branched off dev/kiyoshi-kuromiya, you'd need to rebase onto dev/0.18.1. Let me know if you'd prefer to avoid the rebase and just have this ship in v0.19.0.

[kingfink]

Thanks for the review @jtcohen6 ! I added a test and moved my notes in the changelog to v0.19.0.

[jtcohen6]

Thanks for the contribution @kingfink!