[BUGFIX] Catch exceptions during extension update check

For each extension the available update versions are checked. This
also tries to resolve the extension version dependencies according to
the current system. There might be updates which collide and
exceptions are thrown. This patch catches thrown exceptions as the
update check shouldn't break the Extension Manager.

Resolves: #68585
Releases: master, 6.2
Change-Id: Idc1ed32304dc71dbfe722b3f2c32664f9928cb36
Reviewed-on: http://review.typo3.org/42042


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>