Feature/support android file choose

[briandr97]

Hi @KevinnZou thank you for creating this library. I'm using this in Compose Multiplatform and have encountered a problem.
In my service, I need to get some images from device. And on Android, the file chooser isn't opened in the WebView unless we implement onShowFileChooser. So I added code to override onShowFileChooser in the WebChromeClient. I'm on a deadline, so I was wondering if you could please reflect this change?

Key Changes:

• override WebChromeClient's onShowFileChooser on Android side.
• add sample for choose files

Result:

[KevinnZou]

@briandr97 Thanks for your contribution! You did a great job! However, we may not be able to merge this PR. The reason is that you have directly created a FileChoosableWebChromeClient and implemented file selection capabilities within this PR. However, for other developers, they might prefer to implement file selection in a different style. If we lock down a specific implementation, it will make the library less flexible, which is why we have not provided support for custom capabilities like this. We encourage developers to fork our library and add custom features. Of course, there is a solution to this problem, which is to allow developers to provide custom AccompanistWebViewClient and AccompanistWebChromeClient. In that case, you can achieve this requirement by providing your own FileChoosableWebChromeClient. If you are interested, you can try modifying your PR to this solution. Thank you again.