Problems with WasmExecutor

[flexyyyapk213]

In the 'WasmExecutor' class, I found miscalculations in the code.

1. def exec(self, code: str, globals: dict = {}, locals: dict = {}):
   Mutable default arguments are generated, which is considered an error because they can be shared between calls.
   My proposal:

def exec(self, code: str, globals: Optional[dict] = None, locals: Optional[dict] = None):
    if globals is None:
        globals = {}
    if locals is None:
        locals = {}

2. exec_code = f'exec("""{dedent(code)}""", {globals}, {locals})'
   If the user passes:
   """
   import os
   """
   The string will break.
   My proposal:

import json
# ...
exec_code = f'exec({json.dumps(dedent(code), ensure_ascii=False)}, {globals}, {locals})'

json handles this correctly
3. self.config.argv = ("python", "-c", exec_code)
This is bad because it is slow and consumes a lot of resources in terms of memory.
I propose loading the python runtime and keeping it alive until the instance is destroyed or keeping it as a class attribute so it is created once and for all.