Migrate SelfGrantableRoles to new Plugin structure

backend/src/plugins/SelfGrantableRoles/util/findMatchingRoles.ts

@@ -0,0 +1,15 @@
+import { TSelfGrantableRoleEntry } from "../types";
+
+export function findMatchingRoles(roleNames, entries: TSelfGrantableRoleEntry[]): string[] {
+  const aliasToRoleId = entries.reduce((map, entry) => {
+    for (const [roleId, aliases] of Object.entries(entry.roles)) {
+      for (const alias of aliases) {
+        map.set(alias, roleId);
+      }
+    }
+
+    return map;
+  }, new Map());
+
+  return roleNames.map(roleName => aliasToRoleId.get(roleName)).filter(Boolean);
+}