[py]: Align error handling to `W3C`

[symonk]

Converts the error codes into a Tuple as they are immutable and adds appropriate type hints for them. Removes unused vars screen & stacktrace as they are redefined later when used.

[AutomatedTester]

Looking at this again we can remove the numbers, that's a hangover from JWP that we are trying to remove anyway

[codecov-commenter]

Codecov Report

Merging #10657 (da85cde) into trunk (744b4bd) will decrease coverage by 0.03%. The diff coverage is 50.64%.

@@            Coverage Diff             @@
##            trunk   #10657      +/-   ##
==========================================
- Coverage   48.42%   48.38%   -0.04%     
==========================================
  Files          84       84              
  Lines        5485     5481       -4     
  Branches      279      279              
==========================================
- Hits         2656     2652       -4     
  Misses       2550     2550              
  Partials      279      279              

Impacted Files	Coverage Δ
py/selenium/webdriver/remote/errorhandler.py	54.60% <50.64%> (+0.11%)	:arrow_up:
py/selenium/webdriver/remote/remote_connection.py	29.78% <0.00%> (-0.71%)	:arrow_down:

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[symonk]

Refactoring the error handling is a bigger task than initially thought; all the tests are parameterised for the (int, str) so the new str only is iterable and unpacking itself into hundreds of parameterised tests :smile: need to keep grinding on this one gradually!

[symonk]

I think the error handling code could use a rewrite to scrub some JWP code, I will do it as a follow up ticket.