[WPT] Move credential-management/ FedCM tests to dedicated directory

This CL moves the remaining FedCM files in
wpt/credential-management/ to a dedicated FedCM directory.

BUG=347026221

Change-Id: I5509615b793a958061db6ddf8de75a267fe877ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5670976
Reviewed-by: Robert Flack <[email protected]>
Commit-Queue: Peter Kotwicz <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1324607}

Author: pkotwicz

credential-management/support/README.md

@@ -0,0 +1,3 @@
+spec: https://fedidcg.github.io/FedCM/
+suggested_reviewers:
+  - npm

fedcm/META.yml

@@ -32,7 +32,7 @@
   assert_equals(cred.token, "account=1234");
 
   const iframe_in_idp_scope = `${alt_manifest_origin}/\
-credential-management/support/fedcm/userinfo-iframe.html`;
+fedcm/support/fedcm/userinfo-iframe.html`;
   const message = await createIframeWithPermissionPolicyAndWaitForMessage(t, iframe_in_idp_scope);
   assert_equals(message.result, "Pass");
   assert_equals(message.numAccounts, 1);