Simplicity execution

Hello everyone, I just wanted to share my experience adding [Simplicity](https://github.com/BlockstreamResearch/SimplicityHL) support to the GDK.

### Motivation

In the future it would be nice to be able to execute Simplicity programs, such as [Options](https://github.com/BlockstreamResearch/simplicity-contracts/tree/main/crates/contracts/src/options), on mobile, so I tried to do that with the Green wallet.

### Results

I forked GDK and added a new command to trigger a test: https://github.com/KyrylR/gdk

I also forked green_android and added integration and instructions on how to build (on Mac): https://github.com/KyrylR/green_android

The most time-consuming build takes around 3,300 seconds on an M3 Pro with 36 GB of RAM.

In the end, I stumbled upon executing the libsimplicity jet; it fails (maybe) somewhere here: https://github.com/BlockstreamResearch/rust-simplicity/blob/935a0abd0b86a72feedba1b117181b6bd0fc419e/src/bit_machine/mod.rs#L438

Would love to hear your feedback, any concerns, etc. Thanks!