[4.0] Move JTable property_exists to hasField method

[wilsonge]

We have added a new method hasField in the JTable class/interface. The intention is to replace all property_exists checks on JTable objects with this method. For more information read the PR that implemented this #20987.

The usage of this should be used across the CMS. Should be a relatively easy issue for someone new to work on

[joomla-cms-bot]

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/21445

closed as having Pull Request #21479

[wilsonge]

That's just covering Table classes. Reopening as we still need to do models (and I think there might be a few places in the views too)

[wilsonge]

Library models and controllers now done. There's some instances in extensions still left to be done