Add google_dns_record_set data source

[techno-tanoC]

ref hashicorp/terraform-provider-google#10906

Added google_dns_record_set data sources.

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)

`google_dns_record_set`

[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.

@ScottSuarez, 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 ( 6 files changed, 208 insertions(+), 18 deletions(-))
Terraform Beta: Diff ( 5 files changed, 190 insertions(+))

[ScottSuarez]

/gcbrun

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 5 files changed, 190 insertions(+))
Terraform Beta: Diff ( 5 files changed, 190 insertions(+))

[techno-tanoC]

OK, I signed the CLA.

[ScottSuarez]

/gcbrun

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 5 files changed, 190 insertions(+))
Terraform Beta: Diff ( 5 files changed, 190 insertions(+))

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAcccDataSourceDnsRecordSet_basic|TestAccDatasourceGoogleServiceNetworkingPeeredDnsDomain_basic|TestAccApigeeEnvironmentIamBindingGenerated|TestAccApigeeEnvironmentIamMemberGenerated|TestAccApigeeEnvironmentIamPolicyGenerated|TestAccCloudbuildWorkerPool_basic|TestAccContainerNodePool_withInvalidUpgradeSettings You can view the result here: https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=247523

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 5 files changed, 190 insertions(+))
Terraform Beta: Diff ( 5 files changed, 190 insertions(+))
TF Validator: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))

[techno-tanoC]

@ScottSuarez
Would you run /gcbrun?

[ScottSuarez]

/gcbrun

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 5 files changed, 190 insertions(+))
Terraform Beta: Diff ( 5 files changed, 190 insertions(+))
TF Validator: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccApigeeEnvironmentIamBindingGenerated|TestAccApigeeEnvironmentIamMemberGenerated|TestAccApigeeEnvironmentIamPolicyGenerated|TestAccCloudbuildWorkerPool_basic|TestAccContainerCluster_withAuthenticatorGroupsConfig You can view the result here: https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=261049

[techno-tanoC]

Hmm, the new test TestAcccDataSourceDnsRecordSet_basic I added doesn't seem to be failing. What should I do next?

[ScottSuarez]

looks good !

Tests is not failing because the previous result was cached.. all looks okay from my end