Add support for vpc network configuration in google_service_directory_endpoint

[lcaggio]

Add support for 'network' flag on ServiceDirectory Endpoint resource.

fixes hashicorp/terraform-provider-google#10057

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• 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.
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• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

serviceDirectory: add support for vpc network configuration in google_service_directory_endpoint.

[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.

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@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 ( 1 file changed, 49 insertions(+))
Terraform Beta: Diff ( 8 files changed, 147 insertions(+), 5 deletions(-))
TF OiCS: Diff ( 4 files changed, 136 insertions(+))

[slevenick]

/gcbrun

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 1 file changed, 49 insertions(+))
Terraform Beta: Diff ( 3 files changed, 146 insertions(+))
TF OiCS: Diff ( 4 files changed, 136 insertions(+))

[slevenick]

Thanks!