API level 21 cherry-pick for blind signing wording

[apaillier-ledger]

Description

#747

Changes include

• Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• Tests
• Documentation
• Other (for changes that might not fit in any category)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.20%. Comparing base (603cf09) to head (b4213a1).
Report is 22 commits behind head on API_LEVEL_21.

Additional details and impacted files

@@               Coverage Diff                @@
##           API_LEVEL_21     #748      +/-   ##
================================================
+ Coverage         60.19%   60.20%   +0.01%     
================================================
  Files                12       12              
  Lines              1726     1729       +3     
================================================
+ Hits               1039     1041       +2     
- Misses              687      688       +1     

Flag	Coverage Δ
unittests	60.20% <ø> (+0.01%)	⬆️

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