fix KVv2 data source when specifying a version

[surian]

Fixes #1612 by using ReadWithData instead of using ?version= in path with Read leading to a bad URL encoding when request is submitted to Vault.

[hashicorp-cla]

All committers have signed the CLA.

[swenson]

This looks great! Would it be possible to add a unit test for this as well?

[surian]

This looks great! Would it be possible to add a unit test for this as well?

I added a unit test. Same test as the current one but testing by providing the version parameter.

Without the patch:

=== RUN   TestDataSourceKVV2Secret
    data_source_kv_secret_v2_test.go:21: Step 2/2 error: Error running pre-apply refresh: exit status 1

        Error: no secret found at "tf-kv-4323879699321682032/data/foo-1286120807726163543?version=1"

          on terraform_plugin_test.tf line 27, in data "vault_kv_secret_v2" "test":
          27: data "vault_kv_secret_v2" "test" {


--- FAIL: TestDataSourceKVV2Secret (4.81s)

With the patch:

=== RUN   TestDataSourceKVV2Secret
--- PASS: TestDataSourceKVV2Secret (7.23s)
PASS

[swenson]

LGTM. Thanks!