Add the use of NSUserDefaults to privacy manifest.

[mvanbeusekom]

Updates the privacy manifest to include the use of the NSUserDefaults API.
The permission_handler stores a boolean value to track if permission to always
access the device location has been requested.

Resolves #1292

Pre-launch Checklist

• I made sure the project builds.
• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is does not need version changes.
• I updated CHANGELOG.md to add a description of the change.
• I updated/added relevant documentation (doc comments with ///).
• I rebased onto main.
• I added new tests to check the change I am making, or this PR does not need tests.
• I made sure all existing and new tests are passing.
• I ran dart format . and committed any changes.
• I ran flutter analyze and fixed any errors.

[TimHoogstrate]

LGTM