feat: add storage bucket resource (#417)

* feat: add storage bucket resource

- Create a new resource for storage bucket
- Add examples and docs for how to use new resource
- Tests added but they do not run on purpose and have not been validated yet because we cannot run tests for enterprise features yet. That will be addressed separately

## Considerations
- Even though only AWS can be supported today, still added the `pluginID` & `pluginName` fields so it's easy to extend once other plugin types are supported
- There is some logic around handling secrets sent to Boundary and validating secret HMAC changes that exist from `boundary_host_catalog_plugin` that was introduced in [PR-159](https://github.com/hashicorp/terraform-provider-boundary/pull/159). Used the same logic we've been using for that

CHANGELOG.md

@@ -4,6 +4,11 @@ Canonical reference for changes, improvements, and bugfixes for the Boundary Ter
 
 ## Next
 
+### New and Improved
+
+* Add support for a storage bucket as a resource
+  ([PR](https://github.com/hashicorp/terraform-provider-boundary/pull/417))
+
 ## 1.1.8 (June 13, 2023)
 
 ### New and Improved