Create packaged emulator compatible with mach.

[brendandahl]

Creates/copies all the necessary files and folders need for a packaged
emulator to work with mach's un-packaging script and emulator starting
script.

[brendandahl]

Can be run with with something like ANDROID_AVD_HOME=/home/bdahl/.mozbuild/android-device/avd /home/bdahl/.mozbuild/android-sdk-linux/emulator/emulator -avd test-1 -gpu on -verbose -show-kernel -ranchu -writable-system -selinux permissive -feature GrallocSync,LogcatPipe,GLAsyncSwap,GLESDynamicVersion,GLDMA,EncryptUserData,IntelPerformanceMonitoringUnit,Wifi,HostComposition,DynamicPartition -memory 3072 -cores 4

[gabrielesvelto]

BTW this is working fine with my TaskCluster builds.

[brendandahl]

@seinlin can we get this merged in? Alternatively, if you don't want us to change package-emulator.sh, I could create a new shell script just for creating mach compatible packages e.g. package-emulator-for-gecko.sh or something.

[gabrielesvelto]

BTW I've got a slightly tweaked version that uses zstd for compression: https://github.com/gabrielesvelto/B2G/blob/kaios-emulator-x86_64/scripts/package-emulator.sh