Replaces our fallback non-OpenSSL MD5 and SHA1 implementations with those from HACL* as we've already done with SHA2.
This builds HACL* as a library in one place. A followup to #101707 which broke some WASM builds. This fixes 2/4 of them, but the enscripten toolchain in the others don't deduplicate linker arguments and error out. A follow-on PR will address those.