Add Messenger/Contexter interface to work Message (and Trace) with errors.As

[morikuni]

Changes

• Add Messenger/Contexer interface to work with errors.As.
• Use pointer internally for Tracer.
• Drop support Go 1.11 and 1.12 because they don't have errors.As method.

Motivation

To be compatible with the standard errors way.

failure.MessageOf and failure.Trace could panic when an error in the error chain calls errors.As in As(interface{}) bool function to delegate to internal errors.

⚠️ Breaking Change ⚠️

If you implements As(interface{}) bool in your error and using type switch with case failure.Tracer, then you should change it to case *failure.Tracer (use pointer).

[codecov-commenter]

Codecov Report

Base: 92.87% // Head: 91.42% // Decreases project coverage by -1.45% :warning:

Coverage data is based on head (a80342d) compared to base (bee906e). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #45      +/-   ##
==========================================
- Coverage   92.87%   91.42%   -1.46%     
==========================================
  Files           6        6              
  Lines         365      373       +8     
==========================================
+ Hits          339      341       +2     
- Misses         20       26       +6     
  Partials        6        6              

Impacted Files	Coverage Δ
failure.go	96.66% <100.00%> (ø)
tracer.go	96.29% <100.00%> (ø)
wrapper.go	90.36% <100.00%> (-3.31%)	:arrow_down:

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