Description:
------------
It is dangerous to store certificates and privateKeys (without a password) on the disk. Unfortunately, this is needed to load the * .p12 file into stream_context_create.

Please, add the option to set certificates and privateKeys from string content or at least from Data URLs, instead the file path only.

Test script:
---------------
// Using string content
// --------------------

openssl_pkcs12_read(file_get_contents('cert.p12'),$certificates,'pass');

$stream_context = stream_context_create(
[ 'ssl' => [ 'local_cert' => $certificates['cert'],
             'local_pk'   => $certificates['pkey']
           ]
]);



// Using Data URLs
// ---------------

openssl_pkcs12_read(file_get_contents('cert.p12'),$certificates,'pass');

$stream_context = stream_context_create(
[ 'ssl' => [ 'local_cert' => 'data:,'.$certificates['cert'],
             'local_pk'   => 'data:,'.$certificates['pkey']
           ]
]);



// Hack: temp files
// ----------------

openssl_pkcs12_read(file_get_contents('cert.p12'),$certificates,'pass');

file_put_contents('cert.temp',$certificates['cert']);
file_put_contents('pkey.temp',$certificates['pkey']);

$stream_context = stream_context_create(
[ 'ssl' => [ 'local_cert' => 'cert.temp',
             'local_pk'   => 'pkey.temp'
           ]
]);

Expected result:
----------------
Reading certificates and privateKeys without temp files.

Actual result:
--------------
Reading certificates and privateKeys only with temp files.