pythongh-95853: Multiple ops and debug for wasm_build.py

- `wasm_build.py` now supports multiple operations.
- only `build` (default) performs auto-building
- new ops `configure` and `compile`.
- better help
- `repl` starts `wasm_webserver` and opens browser repl
- `test` and `hostrunnertest` now support custom testopts

Author: tiran

Makefile.pre.in

@@ -1718,6 +1718,10 @@ buildbottest: all
 		fi
 		$(TESTRUNNER) -j 1 -u all -W --slowest --fail-env-changed --timeout=$(TESTTIMEOUT) $(TESTOPTS)
 
+# Like testall, but directly run Python tests with HOSTRUNNER
+hostrunnertest: all
+		$(RUNSHARED) $(HOSTRUNNER) ./$(BUILDPYTHON) -m test -u all $(TESTOPTS)
+
 pythoninfo: all
 		$(RUNSHARED) $(HOSTRUNNER) ./$(BUILDPYTHON) -m test.pythoninfo