[Tox Support] Additional Changes for tox default environment name for type checking and flake8 configuration

[R7L208]

Default Environment Change

• updating the type environment to type-check which matches the actual environment configuration
• the default environment list wasn't updated when renaming the env to type-check

this is needed because tox list is showing the type default environment which does not exist and type-check as an additional environment.

flake8 Config Change

• flake8 config was defined in .flake8 and tox.ini. The configurations in tox.ini were incomplete and took precedence when running flake8 natively and the linting environment tox -e lint.
• removing the [flake8] config section from tox.ini and migrating all config rules to .flake8 forces tox to look in .flake8 for config rules and does not break the current GH actions

[codecov]

Codecov Report

Merging #321 (8279a5f) into master (44f2235) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #321   +/-   ##
=======================================
  Coverage   85.65%   85.65%           
=======================================
  Files           6        6           
  Lines         767      767           
  Branches      159      159           
=======================================
  Hits          657      657           
  Misses         92       92           
  Partials       18       18           

[tnixon]

LGTM