TYPO3 Core

When a new user first installs TYPO3, they must create the ENABLE_INSTALL_TOOL file before installation can continue. For a friendlier first install, it would be nice to automatically create the file and go directly to the 1-2-3 Install Tool

Solution:
Just before the tslib_fe redirects to the 1-2-3 Install Tool, we can create the missing ENABLE_INSTALL_TOOL file.

• This file will be created anytime there's a redirect to the 1-2-3 Install Tool and not just on initial install. In practice, this should only happen for the initial install but there's no check to prevent it at other times (if anyone thinks this a problem)

• typo3/install/index.php handles the check for the ENABLE_INSTALL_TOOL file and the rest of TYPO3 is not yet initialized at this point so that forces us to create the file as part of the tslib_fe redirect or do a more complex rework of typo3/install/index.php.

(issue imported from #M14719)