Refactor DB Updates handler

[nicodh]

The SqlSchemaMigrationService is removed in 9.5 - so we have to refactor
\EBT\ExtensionBuilder\Utility\ExtensionInstallationStatus->checkForDbUpdate
and
\EBT\ExtensionBuilder\Utility\ExtensionInstallationStatus::performDbUpdates

[liayn]

Is this still open, or can we live with the workaround?

[liayn]

@nicodh See my last question please.

[nicodh]

It's still open. The "workaround" ist skipping the whole update form and show a message that the user has to ckeck db updates himself.
I think we should put it on the "task" list for the new refactoring and upgrades