refactor(anchorSapling): Change type to force consensus rule validation

[oxarbitrage]

Motivation

We want to change the anchorSapling type similar to orchard so range consensus rule is automatically validated.

Close #3528

Solution

Change the type from bytes into jubjub::Fq.

Review

There is a lot of changes needed at different files but they are almost all trivial to me expect the one about sorting. I will like some input maybe from @conradoplg there before marking the pull request as ready for review. I made a comment for this in the code.

Reviewer Checklist

• Code implements Specs and Designs
• Tests for Expected Behaviour
• Tests for Errors

[teor2345]

Looks good, I checked for panics and serialization.

But I want someone else to double-check the cryptography.

[codecov]

Codecov Report

Merging #3544 (d08cfd3) into main (499ae89) will increase coverage by 2.12%.
The diff coverage is 78.71%.

@@            Coverage Diff             @@
##             main    #3544      +/-   ##
==========================================
+ Coverage   78.34%   80.46%   +2.12%     
==========================================
  Files         267      274       +7     
  Lines       31526    32276     +750     
==========================================
+ Hits        24698    25971    +1273     
+ Misses       6828     6305     -523     

[conradoplg]

Looks great! It just needs a couple of fixes

[conradoplg]

Looks good!

[conradoplg]

It seems there's a fake-activation-heights test failing, I can help track it down tomorrow if needed. (There's also another CI failure that seems devops-related)

[dconnolly]

Looks great!