refactor: switch from awsutil to awsutilv2 (#34)

* fix(storage): Storage Assume Role Support

This commit introduces fixes to enable operators to use AWS dynamic
credentials on the storage side of this plugin, namely validation,
improved credential lifecycle management to allow for storage buckets to
be updated from static to dynamic credentials and vice versa, and a new
way to determine credential types.

It also introduces new tests for dynamic credential usage for the
various functions.

* fix(storage): Static rotated creds being deleted on plugin err

On Storage Bucket update, when we determine if the credentials are to be
updated to new ones, we call `credState.ReplaceCreds`.

This call, if the old credentials were managed by us (rotated at create
time), will delete the old credentials and set the new ones onto
credState.

We called this function without validating if the incoming credentials
are valid. This could get the bucket in a state where where, while we'd
return an update error if the incoming credentials weren't working with
S3 (err in the dry run process that happens at the end of the update),
we'd also silently delete the old credentials the bucket used, rendering
the bucket completely broken.

---------

Co-authored-by: Hugo <hugoamvieira@users.noreply.github.com>

testing/e2e_storage_test.go

@@ -75,7 +75,7 @@ func TestStoragePlugin(t *testing.T) {
 	iamSecretAccessKeyMissingPutObject, err := tf.GetOutputString("iam_secret_access_key_missing_put_obj")
 	require.NoError(err)
 
-	// Start the workflow now. Set up the host catalog. Note that this
+	// Start the workflow now. Set up the storage bucket. Note that this
 	// will cause the state to go out of drift above in the sense that
 	// the access key ID/secret access key will no longer be valid. We
 	// will assert this through the returned state.