Add MQL based alerts

[femnad]

This PR adds MQL based alerting for the monitoring alert resource.

Fixes hashicorp/terraform-provider-google#7464

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

monitoring: Added Monitoring Query Language based alerting for `google_monitoring_alert_policy`

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

Thanks for your contribution! A human will be with you soon.

@ndmckinley, please review this PR or find an appropriate assignee.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 3 files changed, 320 insertions(+), 4 deletions(-))
Terraform Beta: Diff ( 3 files changed, 320 insertions(+), 4 deletions(-))
TF Conversion: Diff ( 1 file changed, 82 insertions(+))
Inspec: Diff ( 4 files changed, 95 insertions(+))

[icco]

Note: This is needed for Google's Covid-19 work in google/exposure-notifications-verification-server#810. Both @femnad and myself are Googlers.

[nat-henderson]

Great, I'll run the tests and as long as it all passes we can merge this today. If this is needed for the covid-19 work I can manipulate our release process a little bit and get it out on Monday.

/gcbrun

[modular-magician]

I have triggered VCR tests based on this PR's diffs. See the results here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=154844"

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 3 files changed, 320 insertions(+), 4 deletions(-))
Terraform Beta: Diff ( 3 files changed, 320 insertions(+), 4 deletions(-))
TF Conversion: Diff ( 1 file changed, 82 insertions(+))
Inspec: Diff ( 4 files changed, 95 insertions(+))

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccDataSourceSpannerInstance_basic|TestAccBigQueryJob_bigqueryJobCopyTableReferenceExample|TestAccBigQueryJob_bigqueryJobCopyExample|TestAccBigqueryDataTransferConfig|TestAccKmsCryptoKeyIamBinding|TestAccKmsCryptoKey_basic|TestAccKmsCryptoKeyIamBinding_withCondition|TestAccKmsCryptoKey_template|TestAccKmsCryptoKeyIamMember|TestAccKmsCryptoKeyIamMember_withCondition|TestAccKmsCryptoKeyIamPolicy|TestAccKmsCryptoKeyIamPolicy_withCondition|TestAccMonitoringAlertPolicy You can view the result here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=154848"

[nat-henderson]

LGTM, tests pass.