also str representation of unicode character is different.

this is not used and cause a SyntaxWarning

page templates unicode resolver already takes care of coercing when
needed and this is directly compatible with python2 and python3
Co-authored-by: Kazuhiko SHIOZAKI <kazuhiko@nexedi.com>

This only works on python2

for same reason as the xhtml_style version, there is no problem with
having more than one listbox, see d2dedca3 (core: remove useless log
in Base_callDialogMethod, 2020-07-03)

Use same label as the action, "Preview"

These scripts take time to run, so restrict them to Manager users.

See merge request !1928

See merge request !1915

  The render is useful to preview content after edit while doing a gadget or on other contexts.

  Since corportate identity has erp5_web as dependency, it cause no harm to move.

See merge request !1919

   * const is handled as enum with a single value automatically
   * patch ensureArraySize to not modify the user input, let the user safely slice by himself.
   * Reorganise patches so it is grouped by prototype

Improvements compared to the previous implementation:
- avoid looking up the user document again, when the PAS plugin already did
  that job
- make it possible to call a single script when multiple sources of groups
  are based on the same documents, avoiding iterating unnecessarily on
  those same documents multiple times
- avoid repeating the same membership value (ex: when a user has multiple
  assignments with a common membership subset)
- avoid resolving the same relation more than once
- do not go from document value to relative URL only to go from relative
  URL back to document value at the next step
- move security group id extraction to unrestricted python, as the security
  overhead was taking a large amount of time
In a security setup with 8 scripts (all Assignment-based), 6 base
categories, and 4 Assignments (all valid), this implementation is 10 times
faster at producing the same group id set as the previous one.