CLI tests for logging flags (#3609)

## Issue Addressed
Adding CLI tests for logging flags: log-color and disable-log-timestamp
Which issue # does this PR address?
#3588 
## Proposed Changes
Add CLI tests for logging flags as described in #3588 
Please list or describe the changes introduced by this PR.
Added logger_config to client::Config as suggested. Implemented Default for LoggerConfig based on what was being done elsewhere in the repo. Created 2 tests for each flag addressed.
## Additional Info

Please provide any additional information. For example, future considerations
or information useful for reviewers.

lighthouse/tests/beacon_node.rs

@@ -1454,3 +1454,39 @@ fn monitoring_endpoint() {
             assert_eq!(api_conf.update_period_secs, Some(30));
         });
 }
+
+// Tests for Logger flags.
+#[test]
+fn default_log_color_flag() {
+    CommandLineTest::new()
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert!(!config.logger_config.log_color);
+        });
+}
+#[test]
+fn enabled_log_color_flag() {
+    CommandLineTest::new()
+        .flag("log-color", None)
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert!(config.logger_config.log_color);
+        });
+}
+#[test]
+fn default_disable_log_timestamp_flag() {
+    CommandLineTest::new()
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert!(!config.logger_config.disable_log_timestamp);
+        });
+}
+#[test]
+fn enabled_disable_log_timestamp_flag() {
+    CommandLineTest::new()
+        .flag("disable-log-timestamp", None)
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert!(config.logger_config.disable_log_timestamp);
+        });
+}