refactor(capi): Move CAPI generation to its own crate (#234) * refactor(capi): Move CAPI generation to its own crate * reduce Biscuit visibility * remove capi.rs * add `print_block_source` c binding * add test for `biscuit_print_block_source` + use `inttypes.h` macros for handling cross-platform `uint64_t` type * remove `block()` usage and C-API usage