MissionPlanner: add AI waypoint planner plugin

[Alico12315]

Summary

Add bounded automatic recovery for transient OpenAI-compatible API failures in the AIWaypointPlanner plugin.

Changes

• Update plugin version to 1.5.0 under the repository versioning rules.
• Retry transient HTTP 408, 409, 425, 429, 500, 502, 503 and 504 responses, timeouts and transient transport failures.
• Honor Retry-After and use bounded exponential backoff with cancellation support.
• Preserve response diagnostics and show attempt/reconnection counts.
• Do not retry authentication or invalid-request errors.

Verification

• Release build succeeded with Visual Studio 2022 MSBuild.
• All 26 offline self-tests passed, including transient recovery and permanent 401 handling.
• Mission Planner 1.3.83 started and closed cleanly with the installed v1.5.0 assembly.
• No flight controller was connected and no mission was uploaded.