Revert all SASL authzid (new feature) commits

- Revert all commits related to the SASL authzid feature since the next
  release will be a patch release, 7.65.1.

Prior to this change CURLOPT_SASL_AUTHZID  / --sasl-authzid was destined
for the next release, assuming it would be a feature release 7.66.0.
However instead the next release will be a patch release, 7.65.1 and
will not contain any new features.

After the patch release after the reverted commits can be restored by
using cherry-pick:

git cherry-pick a14d72c a9499ff 8c1cc36 c2a8d52 0edf690

Details for all reverted commits:

Revert "os400: take care of CURLOPT_SASL_AUTHZID in curl_easy_setopt_ccsid()."

This reverts commit 0edf6907ae.

Revert "tests: Fix the line endings for the SASL alt-auth tests"

This reverts commit c2a8d52a13.

Revert "examples: Added SASL PLAIN authorisation identity (authzid) examples"

This reverts commit 8c1cc369d0.

Revert "curl: --sasl-authzid added to support CURLOPT_SASL_AUTHZID from the tool"

This reverts commit a9499ff136.

Revert "sasl: Implement SASL authorisation identity via CURLOPT_SASL_AUTHZID"

This reverts commit a14d72ca2f.

lib/setopt.c

@@ -2400,12 +2400,6 @@ static CURLcode vsetopt(struct Curl_easy *data, CURLoption option,
     break;
 #endif
 
-  case CURLOPT_SASL_AUTHZID:
-    /* Authorisation identity (identity to act as) */
-    result = Curl_setstropt(&data->set.str[STRING_SASL_AUTHZID],
-                            va_arg(param, char *));
-    break;
-
   case CURLOPT_SASL_IR:
     /* Enable/disable SASL initial response */
     data->set.sasl_ir = (0 != va_arg(param, long)) ? TRUE : FALSE;