Nonce simplification

[expede]

• Remove Nonce12 and generate_12
• Nonce16 generation longer takes a seed

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 12.87%. Comparing base (7f680d3) to head (3e8826b).

❗ Current head 3e8826b differs from pull request most recent head 4d8ca6d. Consider uploading reports for the commit 4d8ca6d to get more accurate results

Additional details and impacted files

@@              Coverage Diff              @@
##           v1.0-rc.1      #19      +/-   ##
=============================================
- Coverage      13.00%   12.87%   -0.13%     
=============================================
  Files             68       68              
  Lines           5652     5615      -37     
  Branches        2709     2698      -11     
=============================================
- Hits             735      723      -12     
+ Misses          4313     4304       -9     
+ Partials         604      588      -16     

Files	Coverage Δ
src/delegation/payload.rs	47.48% <ø> (+3.59%)	⬆️
src/invocation/payload.rs	33.13% <ø> (ø)
src/crypto/nonce.rs	57.77% <83.33%> (+5.33%)	⬆️
src/invocation/agent.rs	36.36% <0.00%> (ø)

... and 4 files with indirect coverage changes

[matheus23]

Looking great! :) Thanks!