feat: environment management support

[jharley]

Adds the ability to manage a team's Environments ✨ by introducing a pair of data sources and a shiny new resource.

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1207759682365320

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 75.81395% with 104 lines in your changes missing coverage. Please review.

Project coverage is 80.10%. Comparing base (3ecd18f) to head (72fe570).

Files	Patch %	Lines
internal/provider/environment_resource.go	72.19%	38 Missing and 14 partials ⚠️
client/v2/environments.go	57.74%	21 Missing and 9 partials ⚠️
internal/provider/environments_data_source.go	80.00%	7 Missing and 5 partials ⚠️
internal/provider/environment_data_source.go	89.85%	4 Missing and 3 partials ⚠️
internal/provider/provider.go	60.00%	0 Missing and 2 partials ⚠️
internal/provider/api_key_resource.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #501      +/-   ##
==========================================
- Coverage   80.36%   80.10%   -0.26%     
==========================================
  Files          67       72       +5     
  Lines        5174     5554     +380     
==========================================
+ Hits         4158     4449     +291     
- Misses        753      812      +59     
- Partials      263      293      +30     

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[brookesargent]

Lookin' good! 😎 Just made a couple grammar/typo suggestions.