Special page contributions block log fix

https://wikia-inc.atlassian.net/browse/PLATFORM-470

Added a hook which overrides the default showing of a local log extract for blocked users in case a user is blocked globally using Phalanx. In that case the local log messages does not inform about the actual block and can be confusing, so instead a message that user is blocked globally is displayed.

I'm pretty new to changing MW, so let me know if something should be done differently :)

@michalroszka  @macbre  @wladekb 
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