Merge remote-tracking branch 'kevin/issue/default-dept-private-error' into features_prs/develop-next

Merge remote-tracking branch 'kevin/issue/task-action-button-styling' into features_prs/develop-next

This addresses an issue where the Delete Task Action Button had the wrong
classes which gave it the wrong styling. This corrects the class to make
the Delete button look like the other buttons and still have the red
background on hover.

Merge remote-tracking branch 'kevin/issue/ticket-preview-custom-fields' into features_prs/develop-next

Merge remote-tracking branch 'kevin/issue/disable-canned-responses-on-new-ticket' into features_prs/develop-next

Merge remote-tracking branch 'kevin/issue/local-field-names-in-errors' into features_prs/develop-next

Merge remote-tracking branch 'kevin/issue/private-faq-search-sidebar' into features_prs/develop-next

This addresses issue 4112 where osTicket does not have a default favicon.
This adds favicon images and references to them in the Agent and
Client headers so they appear correctly.