fix(mssql): upsert query with falsey values (#12453)

[patrickcarnahan]

Pull Request check-list

Please make sure to review and check all of these items:

• Does npm run test or npm run test-DIALECT pass with this change (including linting)?
• Does the description below contain a link to an existing issue (Closes #[issue]) or a description of the issue you are solving?
• Have you added new tests to prevent regressions?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Did you update the typescript typings accordingly (if applicable)?
• Did you follow the commit message conventions explained in CONTRIBUTING.md?

Description of change

cherry-pick of #12453

properly determines if a value used in a filter clause for upsert is relevant. currently there is a bug where it treats "falsey" values as not being specified, making it impossible to use something like a default value of 0 in a unique key and then filter by that value.

closes #11902
closes #11684

[patrickcarnahan]

@sushantdhiman thanks for the offer to accept this in v5. after speaking with the azurite project maintainers it would be very helpful to have this fix backported to v5 in order to reduce risk for the change on their side.

[patrickcarnahan]

☝️ was a no-op amend to trigger the appveyor check again. looks like it failed to download the code coverage script. i'll try amending one more time.

[patrickcarnahan]

🤷 not sure if there is anything I can do. Looks like something with coverage in the v5 branch isn't working properly.

[patrickcarnahan]

@sushantdhiman just wanted to check in on this and see if this is still a change you are willing to take to v5.

[patrickcarnahan]

@papb i haven't heard back from @sushantdhiman in a few weeks (maybe he's on vacation or something?) - any chance you're willing to review this backport into v5 discussed here? #12453 (comment)

[patrickcarnahan]

Consumed v6 in azurite so no reason to keep this open.