feat: add tfe_saml_settings data source

[karvounis-form3]

Description

This PR adds the datasource tfe_saml_settings. This change is required in order to add SAML settings support to the provider (documentation). Follow up PR will be to add a resource for tfe_saml_settings.

External links

• List SAML settings API
• Additions to go-tfe PR

Output from acceptance tests

$ TESTARGS="-run TestAccTFESAMLSettingsDataSource_basic" make testacc

TF_ACC=1 TF_LOG_SDK_PROTO=OFF go test $(go list ./... |grep -v 'vendor') -v -run TestAccTFESAMLSettingsDataSource_basic -timeout 15m
?   	github.com/hashicorp/terraform-provider-tfe	[no test files]
=== RUN   TestAccTFESAMLSettingsDataSource_basic
--- PASS: TestAccTFESAMLSettingsDataSource_basic (19.45s)
PASS
ok  	github.com/hashicorp/terraform-provider-tfe/tfe	19.853s
?   	github.com/hashicorp/terraform-provider-tfe/version	[no test files]

[uturunku1]

Wow, this looks great. And I am so glad to see that you are using the terraform-plugin-framework syntax!

[uturunku1]

All tests are passing now! Thank you so much for your contribution @karvounis-form3 . Whenever you are ready, please go ahead and merge your PR (as well close the Github issue).

[karvounis-form3]

@uturunku1 Unfortunately, I do not have proper permissions to merge this PR

This branch has no conflicts with the base branch
Only those with [write access](https://docs.github.com/articles/what-are-the-different-access-permissions) to this repository can merge pull requests.