GraphQL { functions { call } } generic mutation (#5818)

* Generic call function mutation
* Change function return type to any
* First passing test
* Testing errors
* Testing different data types

src/GraphQL/loaders/defaultGraphQLMutations.js

@@ -1,11 +1,13 @@
 import * as objectsMutations from './objectsMutations';
 import * as filesMutations from './filesMutations';
 import * as usersMutations from './usersMutations';
+import * as functionsMutations from './functionsMutations';
 
 const load = parseGraphQLSchema => {
   objectsMutations.load(parseGraphQLSchema);
   filesMutations.load(parseGraphQLSchema);
   usersMutations.load(parseGraphQLSchema);
+  functionsMutations.load(parseGraphQLSchema);
 };
 
 export { load };