Full implementation of MSP OSD

[SolderSyntax]

Describe problem solved by the proposed feature

MSP OSD has been recently re-worked and merged on main (mid-2025).
Still, some features are missing.

List of available display items in PX4: https://docs.px4.io/main/en/advanced_config/parameter_reference.html#OSD_SYMBOLS

I have troubles understanding exactly which items are implemented currently, but at the very least I can say CROSSHAIRS is not.

Describe your preferred solution

Continue implementation of various features of MSP OSD.

Describe possible alternatives

It is advised to continue looking at Betaflight and ArduPilot's implementation, together with OpenIPC repositories to gain understanding of methods to complete the task.

Additional context

Latest major PR:
#24695

Thanks to @Li-Tianming for the efforts of getting this feature back to working condition.
No response

[hamishwillee]

@SolderSyntax If you know something about this topic, would you be interested in helping address #25237 ?