[AdbRunner] Add ADB forward port management (follow-up to #305)

[rmarinho]

Summary

Adds the symmetric forward-port pair to the reverse-port methods that landed in #305. Same AdbPortSpec / AdbPortRule / AdbProtocol types — just four new methods. Discussed in #305 (comment).

Method	adb command
ForwardPortAsync(serial, local, remote)	adb -s <serial> forward <local> <remote>
RemoveForwardPortAsync(serial, local)	adb -s <serial> forward --remove <local>
RemoveAllForwardPortsAsync(serial)	adb -s <serial> forward --remove-all
ListForwardPortsAsync(serial)	adb forward --list (filtered by serial)

Why we need this in addition to reverse

adb forward and adb reverse are not interchangeable — they connect opposite directions:

• reverse <remote-on-device> <local-on-host> — device-side socket forwards to host-side. Used by hot reload (the device app connects to a "device" port that's actually tunnelled to the IDE host).
• forward <local-on-host> <remote-on-device> — host-side socket forwards to device-side. Used when the IDE / harness needs to connect to a service running on the device:
  • JDWP debugger attach — forward tcp:N jdwp:<pid>
  • Performance-tracing endpoints exposed by the runtime
  • DevFlow agent connect — when the in-app agent listens on a device port and the host needs a stable host-side port to reach it

--list output format note

adb forward --list emits one line per rule across all devices in the form <serial> <local> <remote> (different from (reverse) <remote> <local>). ListForwardPortsAsync uses the unscoped adb forward --list and filters to the requested serial in ParseForwardListOutput. Serial match is case-sensitive to match adb's behaviour.

Tests

• 12 new parser tests (ParseForwardListOutput_*) mirroring the reverse parser tests:
  • single rule, multiple rules, serial filtering, empty output, no lines, empty serial, no matching device, malformed line, non-tcp specs, Windows line endings, tab separation, case-sensitivity.
• 7 new parameter-validation tests covering empty serial / null spec for the four new public methods.

All Forward + Reverse tests pass locally (36/36). Full suite has one pre-existing unrelated JdkDirectory_JavaHome failure on main that's not touched by this PR.

Consumers

• VS Code MAUI extension ServiceHub→CLI migration — forwardPort in MauiAndroidPlatform.ts (debugger configurations, perf tooling).
• MAUI DevTools CLI (dotnet/maui-labs#197) — maui android port forward … group, sibling of the existing reverse surface.
• Visual Studio ClientTools.Platform — same paths that drive reverse today have parallel forward call-sites.

Public API additions

virtual Xamarin.Android.Tools.AdbRunner.ForwardPortAsync(string! serial, AdbPortSpec! local, AdbPortSpec! remote, CancellationToken cancellationToken = default) -> Task!
virtual Xamarin.Android.Tools.AdbRunner.ListForwardPortsAsync(string! serial, CancellationToken cancellationToken = default) -> Task<IReadOnlyList<AdbPortRule!>!>!
virtual Xamarin.Android.Tools.AdbRunner.RemoveAllForwardPortsAsync(string! serial, CancellationToken cancellationToken = default) -> Task!
virtual Xamarin.Android.Tools.AdbRunner.RemoveForwardPortAsync(string! serial, AdbPortSpec! local, CancellationToken cancellationToken = default) -> Task!