mgr: tweaks to command permissions

Upgrade all selftest ops to rw, downgrade restful
cert list to r.

Signed-off-by: John Spray <john.spray@redhat.com>
(cherry picked from commit 7602f25)

 Conflicts:
	src/pybind/mgr/selftest/module.py
		Removed self-test commands and changes as per the
		mimic backport.

src/pybind/mgr/restful/module.py

@@ -214,7 +214,7 @@ class Module(MgrModule):
         {
             "cmd": "restful list-keys",
             "desc": "List all API keys",
-            "perm": "rw"
+            "perm": "r"
         },
         {
             "cmd": "restful create-self-signed-cert",