* on RP2350 _dcp variant now enables -msoft-float, since if you're using this at all it is likely because you don't want to use the VFP unit at all (to save stack space)
* implement all float_ and double_ conversion functions in all pico_float_pico_ variants and pico_double_pico on RP2040 and RP2350 (many were missing in some combinations)
* provide better granularity of what functions are wrapped in each case
also marked custom_xxx_funcs_test.c as not in bazel build yet
