refactor: encoding scheme

[Daanvdplas]

For tests pallet/api/src/extension.rs see #272

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.06145% with 16 lines in your changes missing coverage. Please review.

Project coverage is 45.92%. Comparing base (206757b) to head (0f72c05).

Files with missing lines	Patch %	Lines
primitives/src/lib.rs	80.55%	7 Missing ⚠️
runtime/devnet/src/config/api/versioning.rs	0.00%	6 Missing ⚠️
pallets/api/src/extension.rs	98.26%	2 Missing ⚠️
extension/src/functions.rs	90.90%	0 Missing and 1 partial ⚠️

@@             Coverage Diff              @@
##           daan/api     #271      +/-   ##
============================================
+ Coverage     42.59%   45.92%   +3.32%     
============================================
  Files            47       47              
  Lines          4139     4279     +140     
  Branches       4139     4279     +140     
============================================
+ Hits           1763     1965     +202     
+ Misses         2319     2252      -67     
- Partials         57       62       +5     

Files with missing lines	Coverage Δ
extension/src/matching.rs	100.00% <100.00%> (ø)
extension/src/mock.rs	95.23% <100.00%> (+0.11%)	⬆️
extension/src/functions.rs	92.41% <90.90%> (-0.21%)	⬇️
pallets/api/src/extension.rs	91.82% <98.26%> (+43.49%)	⬆️
runtime/devnet/src/config/api/versioning.rs	60.00% <0.00%> (ø)
primitives/src/lib.rs	91.25% <80.55%> (+91.25%)	⬆️

[chungquantin]

LGTM!

[evilrobot-01]

Looks good, thanks.

I added a commit to better explain what is going on via the prepender test.