VcsCommand: Simplify public runCommand()

Get rid of unused workingDirectory (default working
directory will be used) and exitCodeInterpreter.
Simplify internals a bit.

Change-Id: I2a7547e5a594dd7a21f390daeb06778656e9e971
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/cvs/cvsplugin.cpp

@@ -1438,7 +1438,7 @@ CvsResponse CvsPluginPrivate::runCvs(const FilePath &workingDirectory,
     command->addFlags(flags);
     command->setCodec(outputCodec);
     const CommandResult result = command->runCommand({executable, m_settings.addOptions(arguments)},
-                                                     workingDirectory, timeOutS);
+                                                     timeOutS);
     delete command;
 
     response.result = CvsResponse::OtherError;