CMS-4612 Content - Bulk Publish

Updated the behavior of the Publish button in the wizard: removed
dialog.
Added Publish button to the `ContentBrowseToolbar`.
Refactored Publish request and response to handle multiple contents.
Updated the tests.
CMS-4612 Content - Bulk Publish

Removed `PublishContentDialog`.
Fixed problem with selection reset on items update.
Removed obsolete code.
Merge branches 'CMS-4612' and 'master' of github.com:enonic/wem-ce
CMS-4612 Content - Bulk Publish

- added missing import