Rethink module 'onStartup' hooks #312

Is your feature request related to a problem? Please describe.

1. Right now 'onStartup' hooks are executed for enabled modules on Addon-operator startup and on module enablement. We want to use onStartup hooks to run migrations even for disabled modules and only once at startup.

2. The hook with all snapshots executed once after waiting for Synchronization but before 'beforeHelm' is also may be useful.

3. Also, Go hooks should support these behavior.

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