Add support for named tuples to pretty

[darrenburns]

Type of changes

• Bug fix
• New feature
• Documentation / docstrings
• Tests
• Other

Checklist

• I've run the latest black with default args on new code.
• I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
• I've added tests for new code.
• I accept that @willmcgugan may be pedantic in the code review.

Description

Closes #2012

Named tuples will be formatted similarly to dataclasses when formatted using the pretty module. The code for handling this is very similar to dataclasses, but I opted not to try and factor it out as I think it will reduce readability.

[codecov-commenter]

Codecov Report

Merging #2031 (709b6d3) into master (75f4637) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2031   +/-   ##
=======================================
  Coverage   99.81%   99.81%           
=======================================
  Files          71       71           
  Lines        7058     7088   +30     
=======================================
+ Hits         7045     7075   +30     
  Misses         13       13           

Flag	Coverage Δ
unittests	99.81% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
rich/pretty.py	99.73% <100.00%> (+0.02%)	⬆️

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[willmcgugan]

Mainly just detecting if __repr__ has been overriden.

[willmcgugan]

Introspection is tricky

[darrenburns]

Sorry about that - should be ready for another round now @willmcgugan

[willmcgugan]

LGTM