renderjs_ui: us asBoolean in ERP5JS datetime field

This makes ERP5JS's datetime field behave same as python when using
TALES expression for "date_only" and other less used field values.
8 jobs for fix/erp5js-datetime-tales in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-TestRunner1

00:41:06

failed ERP5.PerformanceTest-TestRunner1

00:34:52

failed ERP5.UnitTest-TestRunner1

02:12:48

passed ERP5.UnitTest-Zope2-ForTestRunner1

01:26:15

failed ERP5.UnitTest-TestRunner1

01:45:07

failed ERP5.UnitTest-TestRunner1

01:52:36

failed ERP5.UnitTest-TestRunner1

01:44:33

failed ERP5.UnitTest-TestRunner1

01:49:16