Fix MicroPython badly handling unicode chars (#2018)

## Changes

  * fixed an issue with the **py-editor** related to the new `linebuffer` directive
  * provide in worker hook scope a simple callback that pre-buffers unicode sequences [accordingly to the standard](https://encoding.spec.whatwg.org/#utf-8-bytes-needed) so that the buffer is sent to the terminal only once those sequences are fulfilled
  * test with both `µ` and way more convoluted sequences such as 👩‍❤️‍👨 that the output, if either requested as input or already evaluated from the page works ... in latter case `test = "👩‍❤️‍👨"` completely messes up the program and the resulting string is empty

pyscript.core/package.json

@@ -1,6 +1,6 @@
 {
     "name": "@pyscript/core",
-    "version": "0.4.16",
+    "version": "0.4.18",
     "type": "module",
     "description": "PyScript",
     "module": "./index.js",
@@ -42,7 +42,7 @@
     "dependencies": {
         "@ungap/with-resolvers": "^0.1.0",
         "basic-devtools": "^0.1.6",
-        "polyscript": "^0.12.2",
+        "polyscript": "^0.12.3",
         "sticky-module": "^0.1.1",
         "to-json-callback": "^0.1.1",
         "type-checked-collections": "^0.1.7"