Add internal ipv6 prefix into compute network and subnetwork data source reference attribute

[Hugozys]

… datasource

This PR is to make data_source_google_compute_network and data_source_google_compute_subnetwork include internal_ipv6_range and _internal_ipv6_prefix into their attribute reference respectively when they have dual stack support enabled upon creation.
Added field names are based on REST API reference and compute client protobuf:

• https://cloud.google.com/compute/docs/reference/rest/v1/networks
• https://cloud.google.com/compute/docs/reference/rest/v1/subnetworks
• https://pkg.go.dev/google.golang.org/api/compute/v1#Network
• https://pkg.go.dev/google.golang.org/api/compute/v1#Subnetwork

Release Note Template for Downstream PRs (will be copied)

compute: added `internal_ipv6_range` to `data.google_compute_network` data source and `internal_ipv6_prefix` field to `data.google_compute_subnetwork` data source

[modular-magician]

Hello! I am a robot. It looks like you are a: Community Contributor Googler Core Contributor. Tests will require approval to run.

@rileykarson, a repository maintainer, has been assigned to review your changes. If you have not received review feedback within 2 business days, please leave a comment on this PR asking them to take a look.

You can help make sure that review is quick by doing a self-review and by running impacted tests locally.

[rileykarson]

Few formatting suggestions, after applying these through the UI + confirming there are no surprises in tests this should be good to go!

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

Terraform GA: Diff ( 6 files changed, 26 insertions(+), 1 deletion(-))
Terraform Beta: Diff ( 6 files changed, 26 insertions(+), 1 deletion(-))

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

Terraform GA: Diff ( 6 files changed, 29 insertions(+), 2 deletions(-))
Terraform Beta: Diff ( 6 files changed, 29 insertions(+), 2 deletions(-))

[modular-magician]

Tests analytics

Total tests: 3144
Passed tests 2824
Skipped tests: 318
Affected tests: 2

Action taken

Found 2 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit. Click here to see the affected tests

TestAccDataSourceGoogleSubnetwork|TestAccDataSourceGoogleNetwork

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[modular-magician]

$\textcolor{green}{\textsf{Tests passed during RECORDING mode:}}$
TestAccDataSourceGoogleSubnetwork[Debug log]
TestAccDataSourceGoogleNetwork[Debug log]

Rerun these tests in REPLAYING mode to catch issues

$\textcolor{green}{\textsf{No issues found for passed tests after REPLAYING rerun.}}$

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$\textcolor{green}{\textsf{All tests passed!}}$
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