[util] Update constexpr hash to be FNV-1a

The constexpr_hash.h header has fallen out of use. As constexpr hashing
will be used for IDs with the service locator protocol, update these
hashes to be 32 and 64 bit FNV-1a, and replace the _h user-defined
literal with _id (a 64-bit hash), and _id8 (a 32-bit hash folded down to
8 bits). These are now in the util/hash.h header along with the runtime
hash functions.

src/libraries/util/util.module

@@ -9,7 +9,6 @@ module("util",
     public_headers = [
         "util/basic_types.h",
         "util/bip_buffer.h",
-        "util/constexpr_hash.h",
         "util/counted.h",
         "util/deque.h",
         "util/enum_bitfields.h",