Strip AOT shared libraries when packaging

[grendello]

#6683 introduced LLVM-based toolchain and it appears that the debug data generated during build is much bigger than before.
We should probably strip AOT (and perhaps other) .so libraries on packaging time.

[grendello]

Alternatively, we can pass -S or -s via the LdFlags property of the AotCompiler task (-s strips all the debug symbols and saves around 30%, -S strips just the debug info and saves around 10%)

[jonathanpeppers]

Radek added this at one point:

https://github.com/xamarin/xamarin-android/blob/dccda9898170e7fe979fd7f3e1811061a9b19af7/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.AssemblyResolution.targets#L212-L227

So AOT .so files aren't going through here?

[grendello]

It appears it only affects framework libs? I think adding -s to LdFlags would be faster - we'd save running strip X times