Can't use kivy with briefcase on windows

**Describe the bug**
`briefcase dev -d` is working well
`briefcase run` fails

**To Reproduce**
Steps to reproduce the behavior:
1. clone https://github.com/jgirardet/kivybriefhello
2. create a virtualenv and activate it
3. pip install briefcase
4. briefcase dev -d => ok
5. briefcase run => fail no message
6. PS C:\Users\jim\rien\kivybrief\helloworld> & '.\windows\Hello World\src\python\python.exe' -m helloworld
```
[INFO ] [Logger ] Record log in C:\Users\jim\.kivy\logs\kivy_20-07-15_9.txt
[INFO ] [Kivy ] v1.11.0
[INFO ] [Kivy ] Installed at "C:\Users\jim\rien\kivybrief\helloworld\windows\Hello World\src\\app_packages\kivy\__init__.py"
[INFO ] [Python ] v3.7.6 (tags/v3.7.6:43364a7ae0, Dec 19 2019, 00:42:30) [MSC v.1916 64 bit (AMD64)]
[INFO ] [Python ] Interpreter at "C:\Users\jim\rien\kivybrief\helloworld\windows\Hello World\src\python\python.exe"
[INFO ] [deps ] Successfully imported "kivy_deps.angle" 0.1.9
[INFO ] [deps ] Successfully imported "kivy_deps.sdl2" 0.1.22
[INFO ] [Factory ] 184 symbols loaded
[INFO ] [Image ] Providers: img_tex, img_dds, img_gif (img_sdl2, img_pil, img_ffpyplayer ignored)
[CRITICAL] [Window ] Unable to find any valuable Window provider. Please enable debug logging (e.g. add -d if running from the command line, or change the log level in the config) and re-run your app to identify potential causes
sdl2 - ImportError: DLL load failed: Le module spécifié est introuvable.
File "C:\Users\jim\rien\kivybrief\helloworld\windows\Hello World\src\\app_packages\kivy\core\__init__.py", line 63, in core_select_lib
fromlist=[modulename], level=0)
File "C:\Users\jim\rien\kivybrief\helloworld\windows\Hello World\src\\app_packages\kivy\core\window\window_sdl2.py", line 27, in
from kivy.core.window._window_sdl2 import _WindowSDL2Storage

[CRITICAL] [App ] Unable to get a Window, abort.
Unable to start application 'helloworld'
```
This a usual error in kivy when missing dependencies. I don't think it's a kivy bug since `dev` is working well.
I looked at `app_packages` and every thing seems good.

**Environment:**
- Operating System: windows 10
- Python version: 3.7
- Software versions:
- Briefcase: 0.3.2
- kivy: 1.11.0 (same thing with 2.0.0rc3)

I'm sorry ,I have no idea at all how to help on it.

Related:
* #1484

Reproduce the failure using the reported Windows 10 steps, comparing `briefcase dev -d` with `briefcase run` and the generated `windows\Hello World\src\python\python.exe -m helloworld` entry point. Check the reported Kivy window-provider and DLL-load error, and review related issue #1484. Done means the packaged application starts successfully with `briefcase run` on Windows.

Written by the indexing model from the issue text.