[schema] Use TZDatetime for creation_date and modification_date
No work has been done for form fields/widgets since creation_date /
modification_date are by default not editable through the default UI. One may
want to add such feature at some point.
Time will be displayed as UTC, let the end-application decide otherwise by
customizing the tzdatetime printer if desired.
Closes #4848923
\.svn
^build$
^dist$
\.egg-info$
^.tox$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
syntax: regexp
.*/data.*/database/.*
.*/data/ldapdb/.*
.*/data/uicache/
.*/data/cubes/.*/i18n/.*\.po
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
^doc/_build
^doc/js_api/