Setup build environment

1. Add Android rust targets

rustup target add x86_64-apple-darwin x86_64-unknown-linux-gnu x86_64-linux-android aarch64-linux-android armv7-linux-androideabi i686-linux-android

2. Set ANDROID_NDK_HOME

export ANDROID_NDK_HOME=/home/<user>/Android/Sdk/ndk/<NDK version, ie. 21.4.7075529>

Adding new structs and functions

1. Create C safe Rust structs and related functions using safer-ffi

2. Test generated library and bdk_ffi.h file with c language tests in cc/bdk_ffi_test.c

3. Use build.sh and test.sh to build c test program and verify functionality and memory de-allocation via valgrind

4. Update the kotlin native interface LibJna.kt in the bdk-kotlin jvm module to match bdk_ffi.h

5. Create kotlin wrapper classes and interfaces as needed

6. Add tests to bdk-kotlin test-fixtures module

7. Use build.sh and test.sh to build and test bdk-kotlin jvm and android modules