A few fixes for the standard-version

Adds a few fixes to the standard branch (assuming this branch intends to sync with the FIPS204 draft).

Fixes macros for signature and private key sizes in api.h (the macros in params.h appear to be already up-to-date): -> private keys increase by 32 bytes because of increased tr (256 bit to 512 bit) -> signature sizes of the -65 and -87 versions increased as noted in https://groups.google.com/a/list.nist.gov/g/pqc-forum/c/EKoI0u_PuOw/m/xQVnr5D0AQAJ?pli=1
packing.h headers were inconsistent with packing.c, causing warnings/errors with newer gcc-versions.
makes randomized signing (with a random rnd) the default option as described in the FIPS204 draft.
updates sizes and test vector/kat hashes in the .yml files
updates macOS build instructions (homebrew locations changed in newer versions)

pq-crystals / dilithium