STORE 'file' scheme loader: fix try_decode_params() to check ambiguity

The way try_decode_params works in raw more, it would take the first ASN1
that could decode and return a STORE_INFO with the resulting EVP_PKEY.
This change has it go through all the matching ASN1 methods and properly
check if there's more than one match, i.e. an ambiguity.

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/3863)