Add optional dependency on ordering crate

[tcharding]

Add an optional dependency on the ordering crate and implement ArbitraryOrd for Fe32 if the feature is enabled.

[tcharding]

Requested by lightningdevkit/rust-lightning#3195

[tcharding]

Something is wrong with the check api script, @apoelstra now that we removed it in rust-bitcoin what is your thoughts, are we removing it everywhere?

[apoelstra]

Yeah, let's remove it everywhere. These constant breakages I think are unacceptable given the way we were trying to use it. I also never got it to work with my local CI so we never really integrated it that well.

[apoelstra]

utACK a8ceeb6 but the check-API commit should be changed to just remove the script.

[tcharding]

the check-API commit should be changed to just remove the script.

I don't understand this comment, I've rebased on #192 so that CI passes. If #192 is not right lets discuss it over there.

[tcharding]

Rebase only, no code changes.

[apoelstra]

FWIW I'm increasingly skeptical of this. It's not clear that anybody needs it and it increases our feature test matrix.

[tcharding]

I'll close since you are looking into the rust-lightning upgrade to use bech32 v0.11.0 and that is what this was for.