TPT-4577: Merge RDMA VPCs to Main

[yec-akamai]

📝 Description

Part of the RDMA interfaces project (vpc and subnet) is now available in prod. We need to separate them from the proj branch. I check out and cheery pick the VPC related implementations and test from the proj/rdma-interfaces branch. Only the fixtures are regenerated from the test against prod.

✔️ How to Test

make test-unit

make test-int

[Copilot]

Pull request overview

This PR brings RDMA-capable VPC support (and corresponding tests/fixtures) from the proj/rdma-interfaces branch into the main linodego client, exposing a vpc_type field and adding coverage for RDMA create/get/list behaviors.

Changes:

• Add VPCType enum + vpc_type fields to VPC and VPC subnet models, and plumb through VPC create options.
• Add unit tests + fixtures for RDMA VPC create/get and subnet unmarshalling.
• Update integration tests and fixtures to cover RDMA VPC/subnet flows and refreshed API validation responses; add new region capability constant for GPUDirect RDMA.

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vpc.go	Introduces VPCType and adds vpc_type to VPC + create options.
vpc_subnet.go	Adds vpc_type to VPCSubnet for RDMA/regular differentiation.
regions.go	Adds CapabilityGPUDirectRDMA region capability constant.
test/unit/rdma_vpc_test.go	Adds unit coverage for RDMA VPC create/get and subnet vpc_type unmarshal.
test/unit/fixtures/vpc_rdma_get.json	New unit fixture for RDMA VPC GET response.
test/unit/fixtures/vpc_rdma_create.json	New unit fixture for RDMA VPC create response.
test/integration/vpc_test.go	Extends VPC integration tests to validate vpc_type and adds RDMA-specific scenarios.
test/integration/vpc_subnet_test.go	Adds assertions/coverage for subnet vpc_type, including RDMA subnet flow.
test/integration/lke_clusters_test.go	Updates VPC helper callsites for changed createVPC signature.
test/integration/fixtures/TestVPC_WithRDMAType.yaml	New integration cassette covering RDMA VPC create/get/list + cleanup.
test/integration/fixtures/TestVPC_WithRDMATypeAndIPv6_Fail.yaml	New cassette covering expected API failure when RDMA VPC includes IPv6 ranges.
test/integration/fixtures/TestVPC_Subnet_WithRDMAType.yaml	New cassette covering RDMA VPC subnet create/get/list + cleanup.
test/integration/fixtures/TestVPC_Create_Invalid.yaml	Updates invalid-create cassette to match refreshed prod validation behavior.

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[mawilk90]

Referring to our Slack discussion, is it fine with RDMA test fixtures to be included in this PR?

[yec-akamai]

Referring to our Slack discussion, is it fine with RDMA test fixtures to be included in this PR?

The RDMA VPCs are already in prod, so it's fine. I don't include any RDMA interfaces in the release.