Optimize the generation of "app_dir"

[EurynomeKeros]

Issue

• The packaging method defines the startup logic of the application as running the "pyxapp" file
• The execution logic of the "pyxapp" file is to extract it to the system's temporary directory and run the entry file
• Run the packaged executable file, when multiple processes are run in a project or the program itself is executed through "subprocesses", it will cause the startup logic to be repeatedly executed, resulting in "pyxapp" file repeatedly decompressing

Reproduction

• Use multiple processes

from multiprocessing import freeze_support,Process

def test():
    print("hello world")

if __name__=="__main__":
    freeze_support()
    process=Process(target=test)
    process.start()
    process.join()

Use the app2exe command to package it as an application and execute it. The "pyxapp" file will be decompressed twice in the temporary directory of the system

• Run the program itself using "subprocess", such as the pyxel.reset() method

import pyxel

class App:
    def __init__(self):
        pyxel.init(160, 120)
        self.x = 0
        pyxel.run(self.update, self.draw)

    def update(self):
        if pyxel.btnp(pyxel.MOUSE_BUTTON_LEFT):
            pyxel.reset()
        self.x = (self.x + 1) % pyxel.width

    def draw(self):
        pyxel.cls(0)
        pyxel.rect(self.x, 0, 8, 8, 9)

App()

Use the app2exe command to package it as an application and execute it. Whenever the pyxel.reset() method is triggered, the "pyxapp" file will be repeatedly decompressed in the system's temporary directory

Impact

This will lead to performance degradation during the application's runtime and some unknown issues

Optimization

In the startup logic of the application, set an environment variable to record the decompression path of the "pyxapp" file. When the startup logic is triggered again, prioritize obtaining the decompression path from this environment variable to avoid further decompression operations

[EurynomeKeros]

Rename the environment variables to better comply with the pyxel specification and avoid conflicts with other environment variables.It is also possible to set the environment variable as a property of pyxel, just like the "WINDOW_STATE_ENV" property, but I'm not sure if this is redundant because "app_dir" is generated by the program and should not allow users to customize it