Issue/fix 601 location always permission bug

[JDDV]

✨ What kind of change does this PR introduce? (Bug fix, feature, docs update...)

Fixed a bug where locationAlways returned sometimes PermissionStatus.Denied instead of PermissionStatus.Granted.

⤵️ What is the current behavior?

locationAlways now returns somtimes the wrong PermissionStatus.

🆕 What is the new behavior (if this is a feature change)?

locationAlways now returns the correct PermissionStatus.

💥 Does this PR introduce a breaking change?

No

🐛 Recommendations for testing

📝 Links to relevant issues/docs

Issue number #620

🤔 Checklist before submitting

• I made sure all projects build.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy.
• I updated CHANGELOG.md to add a description of the change.
• I followed the style guide lines (code style guide).
• I updated the relevant documentation.
• I rebased onto current master.

[codecov]

Codecov Report

Merging #629 (cafadf0) into master (8350aaf) will increase coverage by 10.28%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##           master      #629       +/-   ##
============================================
+ Coverage   89.71%   100.00%   +10.28%     
============================================
  Files           7         1        -6     
  Lines         107        16       -91     
============================================
- Hits           96        16       -80     
+ Misses         11         0       -11     

Impacted Files	Coverage Δ
..._platform_interface/lib/src/permission_status.dart
...lib/src/permission_handler_platform_interface.dart
..._interface/lib/src/method_channel/utils/codec.dart
...hod_channel/method_channel_permission_handler.dart
...andler_platform_interface/lib/src/permissions.dart
...ler_platform_interface/lib/src/service_status.dart

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[mvanbeusekom]

LGTM % a very small grammar mistake in the changelog description.