[mypyc] Add missing header includes in lib-rt files (#21046)
These headers use objects from `stdbool.h` and `mypyc_util.h` without
including them so they currently rely on the dependencies being included
somewhere earlier in the compiled .c file. However compiling just
`stringwriter_extra_ops.c` or `byteswriter_extra_ops.c` with
`MYPYC_EXPERIMENTAL` defined results in errors.
Added a test to compile every .c file in mypyc/lib-rt individually with
and without `MYPYC_EXPERIMENTAL` defined to catch these issues in the
future. ChatGPT wrote the test and I have verified that removing a
necessary header include fails it.
