decoders: Fix prioritization of decoders via property query

decoders: Fix prioritization of decoders via property query

When a property query string was used, it was not being applied to decoders.
When multiple providers supporting the same algorithm were loaded, it was
undefined which provider would be used when decoding a key, even when a
propquery string was provided.  This fix scores decoder instances based on
property query matching and selects the highest scored decoder instance when
building the decoder chain.

The fake_rsa test provider is updated to support basic encoding and decoding.
A test is added using the fake_rsa provider to ensure that property query
strings are respected when loading decoders.

Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27876)