fix: add proxy URL support to Webview at Rust-side.

[situ2001]

#8441 added support for setting proxy for webview, but it forgot to add proxy_url assignment at Rust-side, which made me figure out why proxyUrl is not working on WebView (it worked on WebViewWindow) for some hours. That is why I opened this PR.

References:

tauri/crates/tauri-utils/src/config.rs

Lines 1734 to 1735 in 4e00b27

	#[serde(alias = "proxy-url")]
	pub proxy_url: Option<Url>,

[github-actions]

Package Changes Through 44943e1

There are 1 changes which include tauri with patch

Planned Package Versions

The following package releases are the planned based on the context of changes in this pull request.

package	current	next
tauri	2.5.1	2.5.2

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