feat(gcp): support universe_domain for GCP kms wrappers and vault config

[7sinStone]

Description
This PR adds support for the universe_domain parameter for GCP KMS usage in Vault. When set, Vault forwards the value to the GCP KMS wrapper so the client uses a custom API domain; if not set Vault keeps using googleapis.com.

Related Issue
Closes #31553

Changes Introduced

• Forward universe_domain from Vault KMS config to the gcpckms wrapper (internalshared/configutil/kms.go).

Backward Compatibility
Default behavior unchanged: if universe_domain is not set, Vault continues to use googleapis.com.

Dependency
This PR depends on a change in go-kms-wrapping that adds WithUniverseDomain. Link: go-kms-wrapping.
I tested locally using a temporary replace in my go.mod. Once the wrapper PR is merged I will update go.mod in this branch to the released tag.

Quick post-merge step (what I will do or maintainers can do):

# after go-kms-wrapping PR merged -> bump dependency
go get github.com/hashicorp/go-kms-wrapping/v2@<commit-or-tag>
go mod tidy
git add go.mod go.sum
git commit -m "go: bump go-kms-wrapping for universe_domain support"
git push

Additional Context
Enables Vault to operate with GCP sovereign/custom endpoints by opt-in config only.

Signed-off-by: Houssein Mnaouar [email protected]

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