Add EnvironmentKeyWritingModifier implementation

[Kyle-Ye]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 65 lines in your changes missing coverage. Please review.
✅ Project coverage is 24.01%. Comparing base (df1ba13) to head (de1add4).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ta/Environment/EnvironmentKeyWritingModifier.swift	0.00%	35 Missing ⚠️
.../Environment/EnvironmentKeyTransformModifier.swift	0.00%	30 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #530      +/-   ##
==========================================
- Coverage   24.05%   24.01%   -0.04%     
==========================================
  Files         505      505              
  Lines       28933    28967      +34     
==========================================
- Hits         6959     6957       -2     
- Misses      21974    22010      +36     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.