build: Build Apk and exclude somes Abi

[cloudfysystems]

I need to build my Apk only with one Abi (arm64).

In the default Flutter build, it is possible, but i cant find a way to do it with shorebird. I need to to reduce the size of my apk.

[eseidel]

shorebird releases get-apks might help?

[qianmo2233]

shorebird releases get-apks might help?

only universal.apk got