Update Rust code generation to produce the jet environment separately

[ivanlele]

Generates a jet implementation for the updated jet trait introduced in BlockstreamResearch/rust-simplicity#351

[ivanlele]

haven't touched Haskell in two years, @claude was very helpful with this PR

[apoelstra]

In 03feaa3:

I think we should drop the rustJetEnvImpl entirely -- this generates a short block like impl JetEnvironment for BitcoinEnv { ... } but (a) it's short, and (b) neither the BitcoinEnv struct nor the JetEnvironment trait are autogenerated.

So let's just get rid of the impl entirely, or rather, move it to normal non-generated rust-simplicity code.

[ivanlele]

In 03feaa3:

I think we should drop the rustJetEnvImpl entirely -- this generates a short block like impl JetEnvironment for BitcoinEnv { ... } but (a) it's short, and (b) neither the BitcoinEnv struct nor the JetEnvironment trait are autogenerated.

So let's just get rid of the impl entirely, or rather, move it to normal non-generated rust-simplicity code.

It should be clearer now. I've also updated BlockstreamResearch/rust-simplicity#351 accordingly

[apoelstra]

Awesome, looks good. I tested with rust-simplicity that this seems to work (there are no syntax errors at least :P)

[apoelstra]

ACK 2ee52e3; successfully ran local tests