Grant 'group:all' permission to create invocations on 'chromium:public'

R=nodir,chanli,vadimsh,ddoman,estaab

Change-Id: If965190635ca2251c87b2c49ed5e6721a61eb1de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352798Reviewed-by: Chan Li <chanli@chromium.org>
Reviewed-by: Erik Staab <estaab@chromium.org>
Commit-Queue: Roberto Carrillo <robertocn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797500}

infra/config/generated/realms.cfg

@@ -150,6 +150,10 @@ realms {
     role: "role/buildbucket.reader"
     principals: "group:all"
   }
+  bindings {
+    role: "role/resultdb.invocationCreator"
+    principals: "group:all"
+  }
 }
 realms {
   name: "try"

infra/config/main.star

@@ -108,6 +108,10 @@ luci.realm(
             roles = "role/buildbucket.reader",
             groups = "all",
         ),
+        luci.binding(
+            roles = "role/resultdb.invocationCreator",
+            groups = "all",
+        ),
         # Other roles are inherited from @root which grants them to group:all.
     ],
 )