Rename EVP_PKEY_get0_first_alg_name to EVP_PKEY_get0_type_name

Rename EVP_PKEY_get0_first_alg_name to EVP_PKEY_get0_type_name

We use type elsewhere and documenting the 'first' in the
name of the call is a little bit superfluous making the
name too mouthful.

Also rename EVP_PKEY_typenames_do_all to
EVP_PKEY_type_names_do_all to keep the words separated by
underscore.

Fixes #14701

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14868)