Remove global state

[drdavella]

Overview

Remove the use of global state; other miscellaneous code cleanup

Description

• The main change here is the removal of global state for storing the working directory
• The DependencyManager also effectively stored global state since it's implemented in terms of a Singleton
• All codemods now receive a CodemodExecutionContext which is used to store centralized state
• This PR also fixes a circular dependency that was exposed when running tests
• I also introduced a Makefile to consolidate some of our testing and linting commands

[drdavella]

We could include integration tests here if we want but mainly I want to avoid running the webgoat tests by accident.

[codecov-commenter]

Codecov Report

Merging #35 (71cf85b) into main (979abed) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #35      +/-   ##
==========================================
+ Coverage   95.67%   95.69%   +0.01%     
==========================================
  Files          38       37       -1     
  Lines        1340     1346       +6     
==========================================
+ Hits         1282     1288       +6     
  Misses         58       58              

Files Changed	Coverage Δ
src/codemodder/change.py	100.00% <ø> (ø)
src/codemodder/__main__.py	96.87% <100.00%> (-0.07%)	⬇️
src/codemodder/codemods/api/__init__.py	95.58% <100.00%> (+0.06%)	⬆️
src/codemodder/codemods/base_codemod.py	95.71% <100.00%> (+0.63%)	⬆️
src/codemodder/codemods/base_visitor.py	96.87% <100.00%> (-0.19%)	⬇️
src/codemodder/codemods/django_debug_flag_on.py	100.00% <100.00%> (ø)
...odder/codemods/django_session_cookie_secure_off.py	98.30% <100.00%> (+0.05%)	⬆️
src/codemodder/codemods/https_connection.py	93.54% <100.00%> (-0.21%)	⬇️
src/codemodder/codemods/order_imports.py	92.85% <100.00%> (-0.63%)	⬇️
...rc/codemodder/codemods/process_creation_sandbox.py	100.00% <100.00%> (ø)
... and 7 more