decodeCertificatePem

Decodes a multiline string that contains a certificate which is rfc_7468. A typical input string looks like this:

-----BEGIN CERTIFICATE-----
MIIBYTCCAQegAwIBAgIBKjAKBggqhkjOPQQDAjApMRQwEgYDVQQLEwtlbmdpbmVl
cmluZzERMA8GA1UEAxMIY2FzaC5hcHAwHhcNNzAwMTAxMDAwMDA1WhcNNzAwMTAx
MDAwMDEwWjApMRQwEgYDVQQLEwtlbmdpbmVlcmluZzERMA8GA1UEAxMIY2FzaC5h
cHAwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAASda8ChkQXxGELnrV/oBnIAx3dD
ocUOJfdz4pOJTP6dVQB9U3UBiW5uSX/MoOD0LL5zG3bVyL3Y6pDwKuYvfLNhoyAw
HjAcBgNVHREBAf8EEjAQhwQBAQEBgghjYXNoLmFwcDAKBggqhkjOPQQDAgNIADBF
AiAyHHg1N6YDDQiY920+cnI5XSZwEGhAtb9PYWO8bLmkcQIhAI2CfEZf3V/obmdT
yyaoEufLKVXhrTQhRfodTeigi4RX
-----END CERTIFICATE-----