Expose pyscript.py_import and js_import for lazy Python/JS modules (#2091)

* Expose pyscript.py_modules for lazy Python modules

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

pyscript.core/src/core.js

@@ -157,6 +157,7 @@ for (const [TYPE, interpreter] of TYPES) {
         // enrich the Python env with some JS utility for main
         interpreter.registerJsModule("_pyscript", {
             PyWorker,
+            js_import: (...urls) => Promise.all(urls.map((url) => import(url))),
             get target() {
                 return isScript(currentElement)
                     ? currentElement.target.id

pyscript.core/src/stdlib/pyscript/__init__.py

@@ -29,6 +29,7 @@
 #     pyscript.magic_js. This is the blessed way to access them from pyscript,
 #     as it works transparently in both the main thread and worker cases.
 
+from polyscript import lazy_py_modules as py_import
 from pyscript.display import HTML, display
 from pyscript.fetch import fetch
 from pyscript.magic_js import (
@@ -37,6 +38,7 @@ from pyscript.magic_js import (
     config,
     current_target,
     document,
+    js_import,
     js_modules,
     sync,
     window,

pyscript.core/src/stdlib/pyscript/magic_js.py

@@ -42,6 +42,10 @@ if RUNNING_IN_WORKER:
         window = polyscript.xworker.window
         document = window.document
         js.document = document
+        # this is the same as js_import on main and it lands modules on main
+        js_import = window.Function(
+            "return (...urls) => Promise.all(urls.map((url) => import(url)))"
+        )()
     except:
         globalThis.console.debug("SharedArrayBuffer is not available")
         # in this scenario none of the utilities would work
@@ -64,7 +68,7 @@ if RUNNING_IN_WORKER:
 
 else:
     import _pyscript
-    from _pyscript import PyWorker
+    from _pyscript import PyWorker, js_import
 
     window = globalThis
     document = globalThis.document