[BUGFIX] Exclude honeypot field in EXT:form from tabbing

When tabbing trough a form in frontend the honeypot textfield was
reachable. Add a tabindex -1 which prevents the cursor to enter the
hidden field.

Resolves: #79688
Releases: master
Change-Id: I0dbdb7911fe4c159236c53dd425a62c9404cd973
Reviewed-on: https://review.typo3.org/51581


Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Josef Glatz <josef.glatz@typo3.org>
Reviewed-by: Ralf Zimmermann <ralf.zimmermann@tritum.de>
Tested-by: Ralf Zimmermann <ralf.zimmermann@tritum.de>
Reviewed-by: Philipp Gampe <philipp.gampe@typo3.org>
Tested-by: Josef Glatz <josef.glatz@typo3.org>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Tested-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>