feat: Add feature to use ksni crate for tray icons on Linux

[dfaust]

Using ksni and the xdg standard for tray icons on Linux unlocks missing functionality and new features (tauri-apps/tray-icon#104 and more), as well as unblocks a GTK4 migration (tauri-apps/webkit2gtk-rs#94).

This PR adds a new feature called linux-ksni, which passes the feature down to the tray-icon crate. I also updated the docs.

For now there is a patch section in the Cargo.toml.

Closes #11293

Companion PR for tray-icon:
Replace libappindicator with ksni: tauri-apps/tray-icon#201

Companion PR for muda:
Export more internals so muda can be used in combination with ksni: tauri-apps/muda#239

[github-actions]

Package Changes Through 92fb26a

There are 6 changes which include tauri-cli with patch, @tauri-apps/cli with patch, tauri-build with patch, tauri with patch, tauri-bundler with patch, tauri-driver 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-bundler	2.2.0	2.2.1
tauri-build	2.0.4	2.0.5
tauri	2.2.0	2.2.1
@tauri-apps/cli	2.2.2	2.2.3
tauri-cli	2.2.2	2.2.3
tauri-driver	2.0.1	2.0.2

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