[FEATURE] Allow flexible configuration for BE submodules

Previously Backend modules could be configured
via a conf.php file that had $MCONF and $MLANG
variables. Additionally, a Extbase extension could
add more configuration via another API method.
However, the building of the module list
(ModuleLoader) and the internal rendering for
ExtJS (ModuleMenuView) is quite tricky and hard
to override.

The public API call
ExtensionManagementUtility::addModule() has another
parameter now to ship additional configuration that will
override $MCONF from conf.php, or even replace
that information completely, so conf.php will be obsolete.

This is a prerequisite for overriding the configuration
"navigationComponentId" to allow the page tree in other areas
than the web module. Additionally, if the new option
"inheritNavigationComponentFromMainModule" is set to
FALSE (TRUE if not set), then e.g. a web_* module can have
the page tree disabled.

Resolves: #49643
Releases: 6.2
Change-Id: I9790e5e40cbc350925d817846d75ab27ec065255
Reviewed-on: https://review.typo3.org/21850
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Felix Kopp
Tested-by: Felix Kopp