Launch Webview on Linux/MacOS

So to give some history, I've mostly finished adding a webview via Rust's wry library, see https://github.com/07th-mod/python-patcher/pull/186. It is more complicated than it should be, because I need to figure out the port the python script has launched on, and pass the information from Python to Rust via a file.

In addition, this only currently works on Windows, because we only produce the rust install loader on Windows - on MacOS and Linux we just distribute the python scripts.

However, recently @andOlga mentioned that there's a much easier way to launch a webview on linux, which is essentially the same thing that wry does, which is to just directly call `msedge` to launch a webview like:

```python
subprocess.run([
"C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe",
"--app=https://www.google.com",
"--user-data-dir=c:\\temp\\webview"
])
```

Because we can call this from Python, doing it this would simplify things quite a bit, however given that I've mostly tested and finished the Windows-only Rust version, I will probably just go with that for now. Some of the changes I've made would also still exist even if we use the Rust version.

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Coming back to the point of this issue, If we want to launch Webview on Linux/MacOS, we might be able to use something similar to the above (launched from the Python side):

- On Linux, if chromium is installed we can use that, if not we can just fallback to the web browser
- For MacOS, I'm not sure what program or arguments should be used, but as wry states it uses webkit, so I assume it's available there too

----

Another (better) alternative suggested by andOlga was to use https://github.com/r0x0r/pywebview , which behaves pretty much the same as Rust's wry library.

We need to setup using external libraries in the installer. andOlga suggested shipping venv and activating it before we run the installer. I'm not too sure how venv works, but if we can't directly include the packages in a venv in the installer, we could create a venv and install packages to that venv at runtime, assuming it doesn't make the installer take too long to start up.

Also, if it is possible to use this across all platforms, and it has no missing features from the existing Windows wry based webview, I would just use it across all platforms to keep it consistent and remove our wry webview

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PyOxidizer (https://github.com/indygreg/PyOxidizer) was recommended as a way to deal with distributing python with included libs. Previously I had tried using pyinstaller (can't remember what happened), but I haven't tried pyoxidizer before.

The issue describes adding a webview for Linux and macOS to a Python-based game mod installer. Examine the existing Windows implementation using Rust's wry library in pull request #186. Research pywebview as a cross-platform alternative and PyOxidizer for distribution. The goal is to launch a webview from Python, handling platform-specific browser commands or a library, and integrate it into the installer.

Written by the indexing model from the issue text.