feat/ allow webview2 (windows) to use optional user_data folder provided by the attributes.

[lemarier]

Actually only supported on Windows.
Attention the folder need to exist or webview will failed to run.

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Documentation
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes. Issue #___
• No

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix: #xxx[,#xxx], where "xxx" is the issue number)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:

• On Windows, the default user data folder is the exe path + .WebView2.
• This causes problems with the packaged application as the Program Files is protected and can't be used for cached data.
• This allows us to set a different user data folder when needed.

This is only a demonstration of how we could fix it and feel free to make it better!

If you want me to do any changes let me know!

Also, this is NOT supported yet on macOS & Linux.

Thanks!