More updater fixage

Preserve --dir parameter after updating
Allow more than one copy of a command line parameter in MultiMC
Linux runner script no longer changes current directory, which allows '--dir .'
Fixed unit tests, removed the obsolete one (for some legacy updater command line params that were also removed)
[fixes 63127704]

tests/TestUtil.h

@@ -39,7 +39,7 @@ int main(int argc, char *argv[]) \
 { \
 	char *argv_[] = { argv[0] _MMC_EXTRA_ARGV }; \
 	int argc_ = 1 + _MMC_EXTRA_ARGC; \
-	MultiMC app(argc_, argv_/*, QDir::temp().absoluteFilePath("MultiMC_Test")*/); \
+	MultiMC app(argc_, argv_, true); \
 	app.setAttribute(Qt::AA_Use96Dpi, true); \
 	TestObject tc; \
 	return QTest::qExec(&tc, argc, argv); \