230 signature base serialization fix

[da-tychinin]

Issue: #230

• moved all signature input generation from authing to httping
• added optional authority parameter for authing methods.
• removed Signer calls from httping. Moved them to the upper level - authing
• refactor siginput and desiginput method to make them reflect one another
• desiginput return value changed to map by signature label. According to the RFC the labels must be unique
• added sigbase method to httping. It is now used in both sign and verify authing functions
• authing.test.ts: mock httping methods.
• added RFC test cases

[da-tychinin]

I've fixed the error TS5097 for "build, lint and test" stages. Should work fine now. Integration test will fail because of the different signature-base serialization

[codecov]

Codecov Report

Attention: Patch coverage is 94.11765% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 82.89%. Comparing base (e2b2f6e) to head (4bd7b7d).
Report is 1 commits behind head on development.

Files	Patch %	Lines
src/keri/core/httping.ts	89.65%	3 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #231      +/-   ##
===============================================
+ Coverage        82.86%   82.89%   +0.03%     
===============================================
  Files               46       46              
  Lines             4190     4157      -33     
  Branches          1044     1034      -10     
===============================================
- Hits              3472     3446      -26     
+ Misses             689      682       -7     
  Partials            29       29              

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