refactor: just one URI validator

[dopry]

Fixes #1336

Description of the Change

Add scheme validation with detailed error messaged to AllowedURIValidator, and use in place of RedirectURIValidator

• add support for custom scheme validation error messages.
• deprecate RedirectURIValidator
• deprecate WildcardSet

Checklist

• [X] PR only contains one change (considered splitting up PR)
• [X] unit-test added
• [X] documentation updated
• [X] CHANGELOG.md updated (only for user relevant changes)
• [X] author name in AUTHORS

[codecov[bot]]

Codecov Report

Merging #1345 (3da727f) into master (584627d) will increase coverage by 0.05%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1345      +/-   ##
==========================================
+ Coverage   97.48%   97.54%   +0.05%     
==========================================
  Files          32       32              
  Lines        2111     2120       +9     
==========================================
+ Hits         2058     2068      +10     
+ Misses         53       52       -1     

Files	Coverage Δ
oauth2_provider/models.py	98.90% <100.00%> (+0.26%)	:arrow_up:
oauth2_provider/oauth2_validators.py	94.09% <ø> (-0.02%)	:arrow_down:
oauth2_provider/validators.py	100.00% <100.00%> (ø)

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