Removing experimental configuration for extensions starting with API 0.13

[jjbustamante]

Summary

This PR adds some logic to determine when the experimental mode must be enable when running extensions. Since Platform API 0.13, extensions are no more experimental and pack doesn't need to set the env variable CNB_EXPERIMENTAL_MODE=warn, With this PR pack will evaluate if the API version is less than 0.13 and in such as case it will add the environment variable

Output

Before

Pack enables experimental mode when running against lifecycle < 0.18.x

After

When running with platform API <= 0.12

===> EXTENDING (BUILD)
Running the extender on OS linux from image pack.local/builder/6463666b7974676b7763:latest with:
Container Settings:
  Args: /cnb/lifecycle/extender -app /workspace -log-level debug
  System Envs: CNB_EXPERIMENTAL_MODE=warn CNB_PLATFORM_API=0.12

When running with platform API >= 0.13 the CNB_EXPERIMENTAL_MODE=warn env is not set

===> EXTENDING (BUILD)
Running the extender on OS linux from image pack.local/builder/6e647a67686d6278736d:latest with:
Container Settings:
  Args: /cnb/lifecycle/extender -app /workspace -log-level debug
  System Envs: CNB_PLATFORM_API=0.13

Documentation

• Should this change be documented?
  • Yes, see #___
  • No

Related

Resolves #2066

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.15%. Comparing base (57282c7) to head (c53fbf5).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2125      +/-   ##
==========================================
+ Coverage   69.60%   70.15%   +0.55%     
==========================================
  Files         231      231              
  Lines       17228    17227       -1     
==========================================
+ Hits        11990    12084      +94     
+ Misses       4457     4360      -97     
- Partials      781      783       +2     

Flag	Coverage Δ
os_linux	69.30% <100.00%> (+0.02%)	⬆️
os_macos	65.72% <100.00%> (-<0.01%)	⬇️
os_windows	69.68% <100.00%> (+0.61%)	⬆️
unit	70.15% <100.00%> (+0.55%)	⬆️

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

[natalieparellano]

This looks good @jjbustamante