Add support for Cloud SQL Query Insights

[ve6yeq]

Google Cloud SQL for PostgreSQL recently added the new feature Query Insights that helps detect and diagnose performance issues in SQL instances by examining queries using both historical and near real-time data.

Add the necessary resource keys to enable and configure Cloud SQL Query Insights.

Note: Google CLA in process

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[ve6yeq]

@googlebot I signed it!

[google-cla]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[jcanseco]

Hi @ve6yeq, thank you for taking the time to write this PR. Unfortunately, we don't actually take PRs on this repo, and there doesn't seem to be a way to disable PRs on GitHub to avoid potentially wasting people's time :(

So with that said, I went ahead and opened Issue #399 to track this request. Let us continue the conversation there. In fact, it would help us with prioritization if you could comment on how important this feature is to you (i.e. would you consider this a blocker, friction point, or nice-to-have?)