Required fields and default values (#5835)

* Add field options to mongo schema metadata

* Add/fix test with fields options

* Add required validation failing test

* Add more tests

* Only set default value if field is undefined

* Fix redis test

* Fix tests

* Test for creating a new class with field options

* Validate default value type

* fix lint (weird)

* Fix lint another way

* Add tests for beforeSave trigger and solve small issue regarding the use of unset in the beforeSave trigger

src/Controllers/types.js

@@ -5,6 +5,8 @@ export type LoadSchemaOptions = {
 export type SchemaField = {
   type: string,
   targetClass?: ?string,
+  required?: ?boolean,
+  defaultValue?: ?any,
 };
 
 export type SchemaFields = { [string]: SchemaField };