change getContent behaviour: set empty object/array for required properties/items if parent object/array existed

it allow create json document more schema compatible without additional user inputs

i use it if input not filled

i can only assign value

checkSchemaSimpleType() use schema_arr option instead schema
schemaArrFilteredByDocument() return schema_arr instead schema_object

it modification make code better understandable and allow render more
complex fields which use whole schema_arr.