Fix display position handling in plan route

[Zirochkabila]

Summary

• make navigation map position respect active display position providers
• keep Plan a Route centered correctly when Display position preference is set to Bottom
• extract Display position state transition logic for testability
• add regression tests for provider override and Display position status cycling

Testing

• Attempted:
  JAVA_HOME=/opt/homebrew/Cellar/openjdk@17/17.0.15/libexec/openjdk.jdk/Contents/Home ./gradlew :OsmAnd:compileGplayFreeLegacyArm64DebugAndroidTestJavaWithJavac -x :OsmAnd-java:test -Dorg.gradle.jvmargs=-Xmx6g -Dorg.gradle.vfs.watch=false
• Blocked by unrelated master/OsmAndCore issue:
  EpsgCoordinateTransformer.kt cannot resolve net.osmand.core.jni.CoordinateTransformer.