[renderjs_ui] Implement FormBox field

FormBox receives form definition directly inside its field thanks to modification of hateoas script to include result of renderForm.

Implementation details

New embedded page template was added (gadget_erp5_pt_embedded_form_render) which only passes all arguments directly to the form. Form was not modified thus as many code as possible is reused.
Page:form was modified to accept erp5_document in its arguments. It is because FormBox uses it as direct subgadget.
FormBox.py was modified to fix a bug in case of embedded context - the Form was saving field into a wrong object. Thus validation phase of a FormBox yields FormEditor (as before) but if there is embedded context in the formbox field itself it will pass it to the Editor.

getHateoas renderField was heavily modified to be
- sematically more consistent
- not to use global variables which are defined after function definition (thus are not even clojures)
- shorten and simplify field dictionary construction by exporting common parts
Base_edit was refactored meanwhile implementing FormBox edit (was deleted later because it was not needed)
- the same problems as before - semantics and unreadibility by not using comprehensions and destructive assignment

FormBox with the same document as parent's and with fields directly on the document
FormBox with the same document as parent's but with fields which are not on the document (such as Phone on Person for example)
FormBox with different document than parent's

fix naming of formpage -> page_form gadget to be consistent with other pages
renderered -> rendered (variable name in page_form)
keep name jio_key consistent in every page_template (form page template gadgets)
clean up state dictionaries passed around (define important state variables in advance)