API Key auth for namespaces

[kwadhwa-openai]

What was changed

• Currently namespaces can only be created using client certificates. This PR allows ability to create them with API Key authentication
• Allow specifying cloud API versioning to be able to use new features. This also makes it not break backwards compatibility by keeping the default version as the existing (old) one

Why?

This allows using API Keys to interact with namespaces

Checklist

1. Closes [Feature Request] API Key auth for namespaces #128 Closes [Feature Request] Allow specifying versions for cloud API via provider #129

2. How was this tested:
   `make testacc

3. Any docs updates needed?
   generated the docs

[kwadhwa-openai]

@jlacefie @swgillespie another one :)

[jlacefie]

initial manual run of the test suite passes. running manually due to #131

terraform-provider-temporalcloud-sa git:(terraform_api_key_auth_for_namespaces) ✗ make testacc           
TF_ACC=1 go test ./... -v  -timeout 120m
?       github.com/temporalio/terraform-provider-temporalcloud  [no test files]
?       github.com/temporalio/terraform-provider-temporalcloud/internal/client  [no test files]
=== RUN   TestAccBasicNamespace
=== PAUSE TestAccBasicNamespace
=== RUN   TestAccBasicNamespaceWithApiKeyAuth
=== PAUSE TestAccBasicNamespaceWithApiKeyAuth
=== RUN   TestAccBasicNamespaceWithCertFilters
=== PAUSE TestAccBasicNamespaceWithCertFilters
=== RUN   TestAccNamespaceWithCodecServer
=== PAUSE TestAccNamespaceWithCodecServer
=== RUN   TestAccNamespaceRenameForcesReplacement
=== PAUSE TestAccNamespaceRenameForcesReplacement
=== RUN   TestAccNamespaceImport
=== PAUSE TestAccNamespaceImport
=== RUN   TestAccSpacesBetweenCertificateStrings
=== PAUSE TestAccSpacesBetweenCertificateStrings
=== RUN   TestAccNamespaceWithSearchAttributes
=== PAUSE TestAccNamespaceWithSearchAttributes
=== RUN   TestAccNamespaceImportSearchAttribute
=== PAUSE TestAccNamespaceImportSearchAttribute
=== RUN   TestAccNamespaceWithSearchAttributesUpdate
=== PAUSE TestAccNamespaceWithSearchAttributesUpdate
=== RUN   TestAccNamespaces
--- PASS: TestAccNamespaces (3.72s)
=== RUN   TestAccRegion
--- PASS: TestAccRegion (3.89s)
=== RUN   TestAccBasicUser
=== PAUSE TestAccBasicUser
=== RUN   TestAccBasicUserWithNamespaceAccesses
=== PAUSE TestAccBasicUserWithNamespaceAccesses
=== CONT  TestAccBasicNamespace
=== CONT  TestAccSpacesBetweenCertificateStrings
=== CONT  TestAccNamespaceWithCodecServer
=== CONT  TestAccBasicNamespaceWithCertFilters
=== CONT  TestAccNamespaceImportSearchAttribute
=== CONT  TestAccNamespaceWithSearchAttributes
=== CONT  TestAccBasicNamespaceWithApiKeyAuth
=== CONT  TestAccNamespaceWithSearchAttributesUpdate
=== CONT  TestAccBasicUserWithNamespaceAccesses
=== CONT  TestAccBasicUser
--- PASS: TestAccBasicUser (12.26s)
=== CONT  TestAccNamespaceImport
--- PASS: TestAccBasicUserWithNamespaceAccesses (101.97s)
=== CONT  TestAccNamespaceRenameForcesReplacement
--- PASS: TestAccSpacesBetweenCertificateStrings (109.94s)
--- PASS: TestAccBasicNamespaceWithCertFilters (116.85s)
--- PASS: TestAccBasicNamespace (124.74s)
--- PASS: TestAccBasicNamespaceWithApiKeyAuth (125.74s)
--- PASS: TestAccNamespaceImport (119.65s)
--- PASS: TestAccNamespaceImportSearchAttribute (132.76s)
--- PASS: TestAccNamespaceWithSearchAttributesUpdate (138.78s)
--- PASS: TestAccNamespaceWithSearchAttributes (178.24s)
--- PASS: TestAccNamespaceWithCodecServer (238.09s)
--- PASS: TestAccNamespaceRenameForcesReplacement (216.58s)
PASS
ok      github.com/temporalio/terraform-provider-temporalcloud/internal/provider        327.114s
=== RUN   TestCACertNormalization
--- PASS: TestCACertNormalization (0.00s)
=== RUN   TestUnknownEncodedCAValue
--- PASS: TestUnknownEncodedCAValue (0.00s)
=== RUN   TestNullEncodedCAValue
--- PASS: TestNullEncodedCAValue (0.00s)
=== RUN   TestEncodedCAValue
--- PASS: TestEncodedCAValue (0.00s)
PASS
ok      github.com/temporalio/terraform-provider-temporalcloud/internal/types   (cached)

[kwadhwa-openai]

@jlacefie @captainbeardo @anekkanti ping on this

[anekkanti]

LGTM, except for 1 comment.