[BUGFIX] EXT:form - Setting a custom action does not work

Use the f:form pageUid argument if an "action" property is set in the
form configuration.

Resolves: #70280
Releases: master
Change-Id: Ic32a52d8ef3062aa5b7d230dc7a57627c80c4e25
Reviewed-on: http://review.typo3.org/43754


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Philipp Gampe <philipp.gampe@typo3.org>
Tested-by: Philipp Gampe <philipp.gampe@typo3.org>
Reviewed-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Tested-by: Bjoern Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>