Added SVN commit dialog actions for diff file, add file and revert file.
This is done by commit dialog context menu actions.
SVN commit dialog is now a separate class and moved to a separate file.
Also added SVNCommands class with static methods to access basic SVN actions like geting revision or geting remote URL path for a file.
Also added ItemVersion::MissingVersion control for SVN plugin.
{F8130578}