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 ce528b8

There are 8 changes which include tauri-cli with minor, tauri-runtime with minor, tauri-runtime-wry with minor, tauri-utils with minor, tauri with minor, @tauri-apps/api with minor, @tauri-apps/cli with minor, tauri-bundler 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-apps/api	2.2.0	2.3.0
tauri-utils	2.1.1	2.2.0
tauri-bundler	2.2.3	2.2.4
tauri-runtime	2.3.0	2.4.0
tauri-runtime-wry	2.3.0	2.4.0
tauri-codegen	2.0.4	2.0.5
tauri-macros	2.0.4	2.0.5
tauri-plugin	2.0.4	2.0.5
tauri-build	2.0.5	2.0.6
tauri	2.2.5	2.3.0
@tauri-apps/cli	2.2.7	2.3.0
tauri-cli	2.2.7	2.3.0

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