async: add run_in_executor helper

Author: rnovatorov

enapter/async_/__init__.py

@@ -1,7 +1,9 @@
 from .generator import generator
 from .routine import Routine
+from .run_in_executor import run_in_executor
 
 __all__ = [
     "generator",
     "Routine",
+    "run_in_executor",
 ]

enapter/async_/run_in_executor.py

@@ -0,0 +1,7 @@
+import asyncio
+import functools
+
+
+async def run_in_executor(func, *args, **kwargs):
+    loop = asyncio.get_running_loop()
+    return await loop.run_in_executor(None, functools.partial(func, *args, **kwargs))