Maximum number of files allowed reached

**Update**: See [this comment](https://github.com/beeware/briefcase/issues/646#issuecomment-3369414678) for details on an approach to fix the problem.

**Describe the bug**
The following error shows up:
```
Linking application installer...
light.exe : error LGHT0306 : An error (E_FAIL) was returned while finalizing a CAB file. This most commonly happens when creating a CAB file with more than 65535 files in it. Either reduce the number of files in your installation package or split your installation package's files into more than one CAB file using the Media element.
```

**To Reproduce**
Try to package an application with large dependencies that contains a lot of files (more than 65535).

**Expected behavior**
Briefcase would package the application and split the cab files automatically.

**Environment:**
- Operating System: Windows 10, 64bit
- Python version: 3.8
- Software versions:
- Briefcase: 0.3.5

Start with the linked comment for the proposed approach, then trace Briefcase's Windows installer packaging path. Reproduce packaging with more than 65,535 files and verify that the generated installer splits its files across multiple CAB files instead of failing with LGHT0306.

Written by the indexing model from the issue text.