fix(shorebird_cli): don't run AndroidInternetPermissionValidator if no android project exists

[bryanoltman]

Description

Refactors validators to replace scope with canRunInCurrentContext to allow for cases where shorebird doctor is being run within a project but no Android project exists.

Fixes #988

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (890b70a) 100.00% compared to head (8674203) 100.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #995     +/-   ##
===========================================
  Coverage   100.00%   100.00%             
===========================================
  Files          163        83     -80     
  Lines         4136      3079   -1057     
===========================================
- Hits          4136      3079   -1057     

Files Changed	Coverage Δ
...ib/src/validators/shorebird_flutter_validator.dart	100.00% <ø> (ø)
...ib/src/validators/shorebird_version_validator.dart	100.00% <ø> (ø)
...s/shorebird_cli/lib/src/validators/validators.dart	100.00% <ø> (ø)
packages/shorebird_cli/lib/src/doctor.dart	100.00% <100.00%> (ø)
...idators/android_internet_permission_validator.dart	100.00% <100.00%> (ø)

... and 80 files with indirect coverage changes

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