chore: rename class name for ui delegate

[keiya01]

I'm sorry, I added file upload panel in #545 however I used undeclared class name.
In this PR, I fixed the following error.

thread 'main' panicked at 'Class with name UIFileUploadPanelController could not be found', src/webview/wkwebview/mod.rs:396:17

You can reproduce with the following steps.

1. run cargo run --example multi_window
2. click button
3. panicked

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

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