visibility.h is included globally in PX4 via cmake compile flags.
It contains poisoning the exit() command which is used by gtest
to close the test application. Removing the flag for gtest compilation
fixes the compile error:
gtest.cc:4757:7: error: attempt to use poisoned "exit"

 - fixes #11408
 - cleanup Limits.hpp

 - starts requirements for PX4 modules (hrt, param, etc)

 - explicitly set TOOLCHAIN on all NuttX targets

Co-Authored-By: CUAVcaijie <caijie@cuav.net>

You can now add `DYNAMIC` as an option to `px4_add_module`, which will
cause that module to no longer be compiled into the px4 executable, but
instead produce a separate shared library file, which can be loaded and
executed with the new `dyn` command:

    pxh> dyn ./hello.px4mod start

This will load the shared object file `hello.px4mod` if it wasn't
already loaded, and execute its main function with the given arguments.

Due to limited flash space

due to limited flash space.

Also some general minor sanitizer improvements.

 - fixes #10599

module list is now the same as posix_ocpoc_ubuntu.cmake

- only a few configs done yet

it got moved to drivers/telemetry/hott