pgAdmin 4 commit: Misc fixes for the pgAgent module:

Misc fixes for the pgAgent module:

1) User was allowed to enter start date ahead of end date while scheduling a job. Fixes #2921

2) Datetime picker was not displaying in the grid (sub-node collection control). Fixes #1749

3) Fixed UI issue where validation error was not displaying properly for Datetime control.

Branch
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WEBPACK_DEVEL2

Details
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https://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=ee9df5c2ba9d7bbce01e188af0c4ff9c43a3da93
Author: Murtuza Zabuawala <murtuza.zabuawala@enterprisedb.com>

Modified Files
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.../pgagent/schedules/static/js/pga_schedule.js    | 26 +++++++++++++++---
web/pgadmin/static/js/backform.pgadmin.js          | 31 ++++++++++++++--------
web/pgadmin/static/scss/_backform.overrides.scss   |  7 +++++
3 files changed, 50 insertions(+), 14 deletions(-)