feat: add CachedFfiTransaction::transparent_output_address()

[conradoplg]

Motivation

For lightwalletd support we need to be able to get an address from a transparent output. This requires changing zcash_script which was done in ZcashFoundation/zcash_script#29 and exposing the functionality in zebra_script, which is this ticket.

Specifications

Designs

Solution

Add a CachedFfiTransaction::transparent_output_address() method.

Closes #3149

Review

Not urgent but blocks four other tasks from the lightwalletd epic.

This is a draft since it's blocked on ZcashFoundation/zcash_script#29 merging. But it should be complete and can be reviewed if desired.

Anyone can review, but whoever reviews ZcashFoundation/zcash_script#29 will probably be able to review this quickly.

Reviewer Checklist

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

Follow Up Work

[codecov]

Codecov Report

Merging #3668 (5338bc1) into main (6b31f5b) will increase coverage by 0.01%.
The diff coverage is 89.33%.

@@            Coverage Diff             @@
##             main    #3668      +/-   ##
==========================================
+ Coverage   80.05%   80.07%   +0.01%     
==========================================
  Files         290      290              
  Lines       32795    32866      +71     
==========================================
+ Hits        26255    26318      +63     
- Misses       6540     6548       +8     

[teor2345]

Looks great, I just have some minor suggested tweaks.

[teor2345]

Looks great, thanks!

[conradoplg]

Still WIP because it may be no longer needed, see Discord. I'll confirm it

[teor2345]

I'm approving these changes in case we need them.

[conradoplg]

I'll close this for now, I haven't yet confirmed if zcash_primitives will work for us but that's pretty likely. I'll leave the branch and we can reopen this if needed.