Support verifying signature signed using x5c header about ruby-jwt HOT 10 CLOSED

The "x5c" (X.509 certificate chain) Header Parameter contains the
   X.509 public key certificate or certificate chain [RFC5280]
   corresponding to the key used to digitally sign the JWS.  The
   certificate or certificate chain is represented as a JSON array of
   certificate value strings.  Each string in the array is a
   base64-encoded (Section 4 of [RFC4648] -- not base64url-encoded) DER
   [ITU.X690.2008] PKIX certificate value.  The certificate containing
   the public key corresponding to the key used to digitally sign the
   JWS MUST be the first certificate.  This MAY be followed by
   additional certificates, with each subsequent certificate being the
   one used to certify the previous one.  The recipient MUST validate
   the certificate chain according to RFC 5280 [RFC5280] and consider
   the certificate or certificate chain to be invalid if any validation
   failure occurs.  Use of this Header Parameter is OPTIONAL.

The "x5c" (X.509 certificate chain) parameter contains a chain of one
   or more PKIX certificates [RFC5280].  The certificate chain is
   represented as a JSON array of certificate value strings.  Each
   string in the array is a base64-encoded (Section 4 of [RFC4648] --
   not base64url-encoded) DER [ITU.X690.1994] PKIX certificate value.
   The PKIX certificate containing the key value MUST be the first
   certificate.  This MAY be followed by additional certificates, with
   each subsequent certificate being the one used to certify the
   previous one.  The key in the first certificate MUST match the public
   key represented by other members of the JWK.  Use of this member is
   OPTIONAL.

   As with the "x5u" member, optional JWK members providing key usage,
   algorithm, or other information MAY also be present when the "x5c"
   member is used.  If other members are present, the contents of those
   members MUST be semantically consistent with the related fields in
   the first certificate.  See the last paragraph of Section 4.6 for
   additional guidance on this.