Add deprecating support for removed components getActions method

The fix for the Joomla getActions() method in this pull request https://github.com/joomla/joomla-cms/pull/2728 solved the issues, but is missing deprecating support for the removed getActions method in the component helpers (which are replaced by JHelperContent::getActions(). 

This is now causing issues in 3rd party extensions as reported over here for example: https://github.com/t3framework/t3/issues/249

This pull request re-adds the methods for the getActions checks in the core component helpers. The methods convert the requests to the new JHelperContent::getActions() method and logs the usage of depreciated code.

My apologizes for not adding the deprecating support in the initial pull request. 

Please test this pull request to confirm it is fixing the issues for 3rd party extensions.