Added floor property to position model

[mvanbeusekom]

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

Feature

⤵️ What is the current behavior?

The position object doesn't contain any information about the floor the device on which the device is located. In some cases (i.e. on iOS and if the WiFi supports it) the location services can provide floor information.

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

This pull requests adds the floor property to the position object preparing the interface for platform implementations to provide information about on which floor the device is located (if available).

💥 Does this PR introduce a breaking change?

No

🐛 Recommendations for testing

📝 Links to relevant issues/docs

#562

🤔 Checklist before submitting

• All projects build
• Follows style guide lines (code style guide)
• Relevant documentation was updated
• Rebased onto current develop

[codecov]

Codecov Report

Merging #575 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff             @@
##            master      #575    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           15         1    -14     
  Lines          254        40   -214     
==========================================
- Hits           254        40   -214     

Impacted Files	Coverage Δ
...orm_interface/lib/src/models/location_options.dart
...m_interface/lib/src/enums/location_permission.dart
...rors/permission_request_in_progress_exception.dart
...rs/permission_definitions_not_found_exception.dart
...ce/lib/src/errors/permission_denied_exception.dart
...e/lib/src/errors/already_subscribed_exception.dart
...orm_interface/lib/src/enums/location_accuracy.dart
...terface/lib/src/geolocator_platform_interface.dart
...src/implementations/method_channel_geolocator.dart
...rc/errors/location_service_disabled_exception.dart
... and 3 more

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