refactor!: changed KAFKA_PORT to a ContainerPort (#185)

refactor!: made sure that `KAFKA_PORT` follow the convention of being a
`ContainerPort`

This reverts commit
1c6ba59.

It is based on
#183
=> if said PR is merged, the unrelated changes (included to make
merge-conflicts less likely) will merge/rebase away and only the kafka
changes are left.

---------

Co-authored-by: Artem Medvedev <i@ddtkey.com>

src/kafka/mod.rs

@@ -11,7 +11,7 @@ const TAG: &str = "6.1.1";
 /// Can be rebound externally via [`testcontainers::core::ImageExt::with_mapped_port`]
 ///
 /// [`Kafka`]: https://kafka.apache.org/
-pub const KAFKA_PORT: u16 = 9093;
+pub const KAFKA_PORT: ContainerPort = ContainerPort::Tcp(9093);
 /// Port that the [`Zookeeper`] part of the container has internally
 /// Can be rebound externally via [`testcontainers::core::ImageExt::with_mapped_port`]
 ///
@@ -33,7 +33,10 @@ impl Default for Kafka {
         );
         env_vars.insert(
             "KAFKA_LISTENERS".to_owned(),
-            format!("PLAINTEXT://0.0.0.0:{KAFKA_PORT},BROKER://0.0.0.0:9092"),
+            format!(
+                "PLAINTEXT://0.0.0.0:{port},BROKER://0.0.0.0:9092",
+                port = KAFKA_PORT.as_u16(),
+            ),
         );
         env_vars.insert(
             "KAFKA_LISTENER_SECURITY_PROTOCOL_MAP".to_owned(),
@@ -45,7 +48,10 @@ impl Default for Kafka {
         );
         env_vars.insert(
             "KAFKA_ADVERTISED_LISTENERS".to_owned(),
-            format!("PLAINTEXT://localhost:{KAFKA_PORT},BROKER://localhost:9092",),
+            format!(
+                "PLAINTEXT://localhost:{port},BROKER://localhost:9092",
+                port = KAFKA_PORT.as_u16(),
+            ),
         );
         env_vars.insert("KAFKA_BROKER_ID".to_owned(), "1".to_owned());
         env_vars.insert(
@@ -95,7 +101,7 @@ zookeeper-server-start zookeeper.properties &
     }
 
     fn expose_ports(&self) -> &[ContainerPort] {
-        &[ContainerPort::Tcp(KAFKA_PORT)]
+        &[KAFKA_PORT]
     }
 
     fn exec_after_start(
@@ -115,7 +121,7 @@ zookeeper-server-start zookeeper.properties &
             "--add-config".to_string(),
             format!(
                 "advertised.listeners=[PLAINTEXT://127.0.0.1:{},BROKER://localhost:9092]",
-                cs.host_port_ipv4(ContainerPort::Tcp(KAFKA_PORT))?
+                cs.host_port_ipv4(KAFKA_PORT)?
             ),
         ];
         let ready_conditions = vec![WaitFor::message_on_stdout(