[Impeller] Add tooling to make it easier to use vulkan validation layers on android

[dnfield]

Android instructions

Right now, doing the straightforward thing of just copying the libs into android/app/src/main/jniLibs seems to break the --local-engine flag in the tool (at runtime libflutter.so can't be found).

We should see if we can make it easier to do this - this will be important because without the validation layers it's often really hard to figure out what's going wrong on Vulkan on a particular device. We should also have a flag to turn validation on in impeller, which right now requires a custom engine build on Android.

[chinmaygarde]

I've been following the instructions in https://github.com/flutter/engine/blob/main/impeller/docs/android_validation_layers.md for enabling validations.

[dnfield]

Ahh those are using vklibs instead of jniLibs which probably plays better with the tooling.

[chinmaygarde]

So, I just tried it your way (I didn't look at those docs first) and it worked for me that way too.

[dnfield]

It works but I get a runtime exception about not finding libflutter.so if I don't manually copy it over