apps/asn1parse: improve RFC7462 compliance

apps/asn1parse: improve RFC7462 compliance

The asn1parse command now supports three different input formats:

     openssl asn1parse -inform PEM|DER|B64

       PEM: base64 encoded data enclosed by PEM markers (RFC7462)
       DER: der encoded binary data
       B64: raw base64 encoded data

The PEM input format is the default format. It is equivalent
to the former `-strictpem` option which is now marked obsolete
and kept for backward compatibility only.

The B64 is equivalent to the former default input format of the
asn1parse command (without `-strictpem`)

Fixes #7317

Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7320)