Refactoring and simplification for v0.11

[dr-orlovsky]

This PR summarizes 4 moth of Bitfinex team work on simplifying v0.11 branch, including changes coming from dependencies PR:

• Refactoring v0.11 into v0.11.1 in style of v0.12 simplifications rgb-core#288
• Backporting most of v0.12 into v0.11 BP-WG/bp-core#116

[codecov]

Codecov Report

Attention: Patch coverage is 16.78445% with 1884 lines in your changes missing coverage. Please review.

Project coverage is 26.8%. Comparing base (670a7b6) to head (cce223e).
Report is 297 commits behind head on master.

Files with missing lines	Patch %	Lines
src/contract/builder.rs	0.0%	510 Missing ⚠️
src/contract/data.rs	0.0%	329 Missing ⚠️
src/persistence/stock.rs	4.8%	297 Missing ⚠️
src/persistence/memory.rs	3.0%	128 Missing ⚠️
src/indexers/electrum_blocking.rs	0.0%	80 Missing ⚠️
src/stl/specs.rs	23.1%	70 Missing ⚠️
src/containers/consignment.rs	0.0%	54 Missing ⚠️
src/indexers/any.rs	0.0%	52 Missing ⚠️
src/containers/anchors.rs	0.0%	49 Missing ⚠️
src/contract/merge_reveal.rs	0.0%	43 Missing ⚠️
... and 21 more

❌ Your patch check has failed because the patch coverage (16.8%) is below the target coverage (60.0%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #311     +/-   ##
========================================
+ Coverage    19.5%   26.8%   +7.3%     
========================================
  Files          40      37      -3     
  Lines        8453    5710   -2743     
========================================
- Hits         1652    1531    -121     
+ Misses       6801    4179   -2622     

Flag	Coverage Δ
rust	26.8% <16.8%> (+7.3%)	⬆️

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