core: deprecate and replace ap_get_basic_auth_pw

  *) core: Deprecate ap_get_basic_auth_pw() and add 
    ap_get_basic_auth_components(). 

Submitted By: Emmanuel Dreyfus <manu netbsd.org>, Jacob Champion, Eric Covener
CVEID: CVE-2017-3167


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1796348 13f79535-47bb-0310-9956-ffa450edef68
