Windows: Add icon to servo.exe

[UK992]

Based on #11969

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• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors

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This change is 

[highfive]

Heads up! This PR modifies the following files:

• @wafflespeanut: python/servo/package_commands.py, python/servo/build_commands.py
• @paulrouget: components/servo/servo.exe.manifest, ports/servo/build.rs, ports/servo/platform/windows/servo.exe.manifest, ports/servo/Cargo.toml

[jdm]

Looks like some more cfg magic will be necessary:

error[E0433]: failed to resolve. Use of undeclared type or module `winres`
  --> ports/servo/build.rs:21:23
   |
21 |         let mut res = winres::WindowsResource::new();
   |                       ^^^^^^ Use of undeclared type or module `winres`
error: aborting due to previous error
error: Could not compile `servo`.

[jdm]

@bors-servo r+
Thanks for looking into this!

[bors-servo]

📌 Commit 13ce5c2 has been approved by jdm

[bors-servo]

⌛ Testing commit 13ce5c2 with merge 840c44e...

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel-css, linux-rel-wpt, mac-dev-unit, mac-rel-css1, mac-rel-css2, mac-rel-wpt1, mac-rel-wpt2, mac-rel-wpt3, mac-rel-wpt4, windows-msvc-dev
Approved by: jdm
Pushing 840c44e to master...