Decouple filepaths from rcS/MTD using Kconfig rootpath

[PetervdPerk-NXP]

Removes hardcoded filepaths allows for use of filesystem and boardspecific filelocations.

Replaces #21891

[davids5]

@PetervdPerk-NXP - Rebased on man and added the rest of the paths.

[davids5]

@PetervdPerk-NXP Shal we un-draft this?

[dirksavage88]

I just tested the filepath changes on the CANHUBK3 FMU and the params are there, metadata seems to work better (don't need mavlink over ethernet if telem/uart connection is good).

Had to manually change BOARD_ROOT_PATH to '/fs/microsd' get logging to work, though

[DronecodeBot]

This pull request has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:

https://discuss.px4.io/t/px4-sync-q-a-july-24-2024/39852/1

[sfuhrer]

If I'm not mistaken then this PR broke some CI tests:

[MaEtUgR]

The module documentation CI also fails after this. Here's my suggestion to not trip the parser anymore: https://github.com/PX4/PX4-Autopilot/pull/23499

[Jaeyoung-Lim]

Can we revert this until we fix the path issues with CI?

[PetervdPerk-NXP]

@Jaeyoung-Lim can you rebase on https://github.com/PX4/PX4-Autopilot/pull/23457 that should've fixed it