Fixes string casting of paths that may contains Unicode characters.

[Doflatango]

This PR fixed the user_data_directory string casting, which will causes some unexcepted behaviors if string contains Unicode characters:

1. If the user has permission to create directorys, for example:

Excepted user data directory:

C:\Users\Username\AppData\Roaming\myapp\缓存

Actually user data directory:

C:\Users\Username\AppData\Roaming\myapp\￧ﾼﾓ￥ﾭﾘ

The WebView2 will creates the directory as a garbled name ￧ﾼﾓ￥ﾭﾘ, which is unexcepted.

2. If the user does not have write permission, for example, a windows username with Unicode characters:

Excepted user data directory:

C:\Users\缓存\AppData\Roaming\myapp\weview\cache

Actually user data directory:

C:\Users\￧ﾼﾓ￥ﾭﾘ\AppData\Roaming\myapp\weview\cache

This time the Weview2 will try to create directories C:\Users\￧ﾼﾓ￥ﾭﾘ and may got failed.

[Doflatango]

Hi @jnschulze i have updated the comments, please have a look at it.

[jnschulze]

Thanks!