Extend csv tests and register as an example

Author: MattAlp

x-pack/plugin/esql/qa/testFixtures/src/main/resources/ip.csv-spec

@@ -181,6 +181,25 @@ eth0           |gamma          |fe80::cae2:65ff:fece:feb9
 eth0           |epsilon        |[fe80::cae2:65ff:fece:feb9, fe80::cae2:65ff:fece:fec0, fe80::cae2:65ff:fece:fec1]|fe80::cae2:65ff:fece:fec1|fe80::cae2:65ff:fece:fec1
 ;
 
+networkDirectionSimple
+
+FROM hosts |
+WHERE mv_count(ip0) == 1 AND mv_count(ip1) == 1 |
+EVAL direction = network_direction(ip0, ip1, ["loopback"]) |
+KEEP ip0, ip1, direction
+;
+
+
+ip0:ip                    | ip1:ip                    | direction:keyword
+127.0.0.1                 | 127.0.0.1                 | internal
+::1                       | ::1                       | internal
+127.0.0.1                 | ::1                       | internal
+127.0.0.1                 | 127.0.0.2                 | internal
+127.0.0.1                 | 128.0.0.1                 | outbound
+fe80::cae2:65ff:fece:feb9 | fe81::cae2:65ff:fece:feb9 | external
+fe80::cae2:65ff:fece:feb9 | 127.0.0.3                 | inbound
+;
+
 cidrMatchSimple
 
 from hosts | where cidr_match(ip1, "127.0.0.2/32") | keep card, host, ip0, ip1;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/ip/NetworkDirection.java

@@ -52,7 +52,7 @@ public class NetworkDirection extends EsqlScalarFunction {
     @FunctionInfo(
         returnType = "keyword",
         description = "Returns true if the direction of the source-to-destination-IPs is determined to be inbound, provided a list of internal networks.",
-        examples = @Example(file = "ip", tag = "cdirMatchMultipleArgs") // TODO make an example
+        examples = @Example(file = "ip", tag = "networkDirectionSimple")
     )
     public NetworkDirection(
         Source source,

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/scalar/ip/NetworkDirectionTests.java

@@ -75,7 +75,7 @@ public static Iterable<Object[]> parameters() {
                         List.of(
                             new TestCaseSupplier.TypedData(EsqlDataTypeConverter.stringToIP("0.0.0.0"), DataType.IP, "source_ip"),
                             new TestCaseSupplier.TypedData(EsqlDataTypeConverter.stringToIP("0.0.0.0"), DataType.IP, "destination_ip"),
-                            new TestCaseSupplier.TypedData(new BytesRef("unspecified"), stringType, "internal_networks") // TODO: unspecified causes errors
+                            new TestCaseSupplier.TypedData(new BytesRef("unspecified"), stringType, "internal_networks")
                         ),
                         "NetworkDirectionEvaluator[sourceIp=Attribute[channel=0], destinationIp=Attribute[channel=1], networks=Attribute[channel=2]]",
                         DataType.KEYWORD,