Report post controller and report helper require specific implementation of config class

Not sure if there is a specific reason for this we're missing (entirely possible), but we've extended the phpbb/config/config class and it's causing problems with the Report Post functionality. Both phpbb\report\controller\report and phpbb\report\report_handler expect a configuration object of type phpbb/config/db, which means we can't override the config object with our own object extending from phpbb/config/config.

Changing the constructors to accept phpbb/config/config instead seems to work fine for our implementation. I can provide a pull request with the changes, but first I wanted to ask if this change made sense or if there was a specific reason for being so specific in the constructor.