entropy-tss should no longer be a library crate

[ameba23]

Merging #775 means integration tests no longer need entropy-tss as a dependency, and it does not need to be a library crate.

The advantage of turning it back into a binary crate is the full API will be documented when we publish the crate, not just the public parts exposed in the library, which following #775 is basically nothing.

[ameba23]

As discussed with Jesse, i started trying to do this an hit problems, and we decided to abandon it for now.

entropy-testing-utils does still use entropy-tss as a library for running the tss servers in tests, (see tss_server_process.rs) and since this is used also in our integration tests we can't move it inside entropy-tss.

Ideally, tss_server_process.rs should only be used for unit tests, and the integration tests should start the tss servers as OS processes using std::process::spawn.

But i think until we get to a point were we have someone who is complaining about the lack of online API docs for entropy-tss, its not worth doing.

Im leaving this open for now but its not a priority.

[HCastano]

@ameba23 doesn't think this is relevant anymore.