How to have Blender run my script from the filesystem rather than the script window? I'm trying to figure out a workflow to allow me to develop addons in Blender that doesn't require me to use the Scripting window.  The scripting window is great if your script can be done in a single page, but breaks down when you need to break your code into more than one file.  It also causes problems because what you have in the script window may get out of sync with what you have saved to disk.
The only alternative  I see is to keep recompiling/uninstalling/reinstalling my addon.  (By recompile, I mean running a script I've created to bundle my source files into a zip ready for deployment).  However, it takes a lot of mouse clicks in the Preferences dialog to remove your old addon and then install the latest version.  That's a lot of work to do every time you make a change.
I'm seeing some references to 'reloading addons' by pressing F8 in other posts, but I don't see how that will help since I would still need to rebuild/reinstall my plugin.
Is there a more developer friendly way to go about developing an addon?
Have a look at Blender's add-ons folder for many examples.  C:\Program Files\Blender Foundation\Blender 2.91\2.91\scripts\addons if you are on Windows.
Let's have a look at MeasureIt add-on for example. It has multiple files:

If you open the __init__.py, you can see that measureit_main is imported

and if you open it, you can see other imports:

.zip files that you use to install the add-ons are just simple zip files containing a folder named after the add-on and all the files in it.
You could also have a look at How to run a python script external to Blender to run bpy commands in Blender&#39;spython console