Correctly add customize_hostname_check to ssl options

Follow-up to #11344

Prior to this fix, the `customize_hostname_check` option was incorrectly
added to the general options passed to `httpc:request`, which results in
the following error when the request is made:

```
[debug] <0.1.0> Enabling wildcard-aware hostname verification for HTTP client connections
[notice] <0.1.0> Invalid option {customize_hostname_check,
[notice] <0.1.0>                    [{match_fun,#Fun<public_key.6.112534691>}]} ignored
[notice] <0.1.0>
```

With this fix, you can see that `customize_hostname_check` is added to
the `ssl` section of the options:

```
1> redbug:start("rabbit_auth_backend_http:ssl_options->return").
...
...
...
% rabbit_auth_backend_http:ssl_options/0 -> [{ssl,
                                              [{customize_hostname_check,
                                                [{match_fun,
                                                  #Fun<public_key.6.112534691>}]},
                                               {versions,
                                                ['tlsv1.3','tlsv1.2',
                                                 'tlsv1.1',tlsv1]},
                                               {hibernate_after,6000},
                                               {keyfile,
                                                "key.pem"},
                                               {depth,10},
                                               {crl_check,false},
                                               {certfile,
                                                "certificate.pem"},
                                               {cacertfile,
                                                "ca_certificate.pem"},
                                               {fail_if_no_peer_cert,false},
                                               {verify,verify_peer}]}]
```

(cherry picked from commit 4360e05)

Author: lukebakken

deps/rabbitmq_auth_backend_http/src/rabbit_auth_backend_http.erl

@@ -25,6 +25,8 @@
 
 -define(SUCCESSFUL_RESPONSE_CODES, [200, 201]).
 
+-define(APP, rabbitmq_auth_backend_http).
+
 %%--------------------------------------------------------------------
 
 description() ->
@@ -177,7 +179,7 @@ do_http_req(Path0, Query) ->
     {host, Host} = lists:keyfind(host, 1, URI),
     {port, Port} = lists:keyfind(port, 1, URI),
     HostHdr = rabbit_misc:format("~ts:~b", [Host, Port]),
-    {ok, Method} = application:get_env(rabbitmq_auth_backend_http, http_method),
+    {ok, Method} = application:get_env(?APP, http_method),
     Request = case rabbit_data_coercion:to_atom(Method) of
         get  ->
             Path = Path0 ++ "?" ++ Query,
@@ -188,12 +190,12 @@ do_http_req(Path0, Query) ->
             {Path0, [{"Host", HostHdr}], "application/x-www-form-urlencoded", Query}
     end,
     RequestTimeout =
-        case application:get_env(rabbitmq_auth_backend_http, request_timeout) of
+        case application:get_env(?APP, request_timeout) of
             {ok, Val1} -> Val1;
             _ -> infinity
         end,
     ConnectionTimeout =
-        case application:get_env(rabbitmq_auth_backend_http, connection_timeout) of
+        case application:get_env(?APP, connection_timeout) of
             {ok, Val2} -> Val2;
             _ -> RequestTimeout
         end,
@@ -212,17 +214,10 @@ do_http_req(Path0, Query) ->
     end.
 
 ssl_options() ->
-<<<<<<< HEAD
-    case application:get_env(rabbitmq_auth_backend_http, ssl_options) of
-        {ok, Opts0} when is_list(Opts0) ->
-            Opts1 = [{ssl, rabbit_ssl_options:fix_client(Opts0)}],
-            case application:get_env(rabbitmq_auth_backend_http, ssl_hostname_verification) of
-=======
     case application:get_env(?APP, ssl_options) of
         {ok, SslOpts0} when is_list(SslOpts0) ->
             SslOpts1 = rabbit_ssl_options:fix_client(SslOpts0),
             case application:get_env(?APP, ssl_hostname_verification) of
->>>>>>> 4360e05df (Correctly add `customize_hostname_check` to `ssl` options)
                 {ok, wildcard} ->
                     ?LOG_DEBUG("Enabling wildcard-aware hostname verification for HTTP client connections"),
                     %% Needed for HTTPS connections that connect to servers that use wildcard certificates.
@@ -236,7 +231,7 @@ ssl_options() ->
     end.
 
 p(PathName) ->
-    {ok, Path} = application:get_env(rabbitmq_auth_backend_http, PathName),
+    {ok, Path} = application:get_env(?APP, PathName),
     Path.
 
 q(Args) ->