Print PASS on pass when running standalone test binaries (#3229)

* Add test.batch flag so standalone tests print PASS on pass
* Add comment; use single-dash flag style to match usage elsewhere
* Don't add test.batch for wasmtime
* Skip test.batch unless emulator name is blank
* Remove test.batch flag; buffer test output and show only on verbose or failure
* Remove FAIL when all tests fail to match go test output

src/testing/testing.go

@@ -449,9 +449,7 @@ func (m *M) Run() (code int) {
 		fmt.Println("FAIL")
 		m.exitCode = 1
 	} else {
-		if flagVerbose {
-			fmt.Println("PASS")
-		}
+		fmt.Println("PASS")
 		m.exitCode = 0
 	}
 	return