fsm: improve and convert to interface

[vtolstov]

• logger: fix Fields func for default logger
• logger: remove wrappers support
• logger: remove OmitLogger wrapper
• fsm: convert to interface
• fsm: add wrappers support

Signed-off-by: Vasiliy Tolstov v.tolstov@unistack.org

[codecov]

Codecov Report

Merging #178 (cb743ce) into v3 (4debc39) will decrease coverage by 0.33%.
The diff coverage is 70.75%.

@@            Coverage Diff             @@
##               v3     #178      +/-   ##
==========================================
- Coverage   40.92%   40.60%   -0.33%     
==========================================
  Files          97       97              
  Lines        9250     9163      -87     
==========================================
- Hits         3786     3721      -65     
+ Misses       5126     5109      -17     
+ Partials      338      333       -5     

Impacted Files	Coverage Δ
logger/options.go	55.55% <ø> (-4.45%)	⬇️
logger/default.go	56.49% <36.36%> (-16.07%)	⬇️
fsm/default.go	72.72% <72.72%> (ø)
fsm/options.go	83.33% <83.33%> (ø)
fsm/fsm.go

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