bug Disregarding AndroidSdkRoot, if SdkUseEmbedded is enabled when building for Android.

[IoannisFMG]

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Pull Request Details

In fresh Unity installations the AndroidSdkRoot editor pref is not set. They rather default to the tools installed with the editor (SdkUseEmbedded set to true).

Before the fix, we were unable to build unless a correct SDK path was explicitly set, even if the SdkUseEmbedded option was enabled.

By checking the SdkUseEmbedded boolean first we can mitigate the problem.

The code can be further optimized by getting the set AndroidSdkRoot in an else statement, but I don't know if that's within the scope of this fix.

Test Plan

Test Plan: Add your test plan here

1. Add a non Android SDK path as an Android SDK location in Editor's external tools.
2. Check "Android SDK Tools installed with Unity (recommended)"
3. Try to create a build.
4. The build will stop, failing to find the embedded Android SDK path since it checks for a null or an empty string first.