Search for emulator in ANDROID_HOME

[dfabulich]

Fixes #188

In general, I've been nudging Skip to prefer using the tools installed by Android Studio over Homebrew's tools, and this PR is one example of that.

In a UTM environment following my test plan in skiptools/skip#632 where we've only just installed Xcode, Android Studio, and Skip, Homebrew's ANDROID_HOME in /opt/homebrew/share/android-commandlinetools only contains one directory, cmdline-tools. cmdline-tools/latest/bin contains sdkmanager and avdmanager, but no emulator/emulator and no platform-tools/adb.

In this PR, we first try to find the emulator in ANDROID_HOME. If you've installed Android Studio and clicked Next Next Next as you ran it, Android Studio will have already installed emulator/emulator there.

Skip Pull Request Checklist:

• REQUIRED: I have signed the Contributor Agreement
• REQUIRED: I have tested my change locally with swift test
• OPTIONAL: I have tested my change on an iOS simulator or device
• OPTIONAL: I have tested my change on an Android emulator or device

---

• AI was used to generate or assist with generating this PR. Please specify below how you used AI to help you, and what steps you have taken to manually verify the changes.

---