Add `permissions` argument to memberRoleCreate mutation

What does this MR do and why?

This change introduces a permissions argument to the memberRoleCreate mutation to simplify the frontend usage.

#432566 (closed)

Screenshots or screen recordings

How to set up and validate locally

1. Visit the GraphQL explorer. (e.g. http://gdk.test:3000/-/graphql-explorer)
2. Create a new role with the permissions argument.

   mutation createRole {
     memberRoleCreate(
       input: {groupPath: "flightjs", name: "example", description: "test role", permissions: ["read_vulnerability"], baseAccessLevel: GUEST}
     ) {
       errors
       memberRole {
         id
         name
         description
         readVulnerability
         enabledPermissions
         baseAccessLevel {
           integerValue
           stringValue
         }
       }
     }
   }

3. Verify that the response includes the permission in the enabledPermissions field.

   {
     "data": {
       "memberRoleCreate": {
         "errors": [],
         "memberRole": {
           "id": "gid://gitlab/MemberRole/7",
           "name": "example",
           "description": "test role",
           "readVulnerability": true,
           "enabledPermissions": [
             "READ_VULNERABILITY"
           ],
           "baseAccessLevel": {
             "integerValue": 10,
             "stringValue": "GUEST"
           }
         }
       }
     }
   }

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