feat(logging): Improve AppMap agent logging and config output

The AppMap agent's logging has been enhanced for better readability and
detail. This includes:

- Setting a standardized log format for all messages to
  yyyy-MM-dd HH:mm:ss [thread] AppMap level: message.
- Refining the AppMapConfig toString() method to provide a more
  structured and comprehensive output of the configuration details,
  including name, config file path, and package information.
- Adjusting log levels for system properties output in Agent.java from
  info to debug, and removing a redundant stack trace in debug mode
  for cleaner logs.

Author: dividedmind

agent/src/main/java/com/appland/appmap/Agent.java

@@ -72,8 +72,7 @@ public static void premain(String agentArgs, Instrumentation inst) {
     logger.info("Agent version {}, current time mills: {}",
             implementationVersion, start);
     logger.info("config: {}", AppMapConfig.get());
-    logger.info("System properties: {}", System.getProperties());
-    logger.debug(new Exception(), "whereAmI");
+    logger.debug("System properties: {}", System.getProperties());
 
     addAgentJars(agentArgs, inst);
 

agent/src/main/java/com/appland/appmap/config/AppMapConfig.java

@@ -317,6 +317,8 @@ public static TaggedLogger configureLogging() {
     // tinylog freezes its configuration after the first call to any of its
     // methods other than those in Configuration. So, get everything ready
     // before returning the logger for this class;
+    Configuration.set("writer.format", "{date:yyyy-MM-dd HH:mm:ss} [{thread}] AppMap {level}: {message}");
+
     if (Properties.Debug) {
       Configuration.set("level", "debug");
     }
@@ -365,6 +367,25 @@ private static Path findDefaultOutputDirectory(FileSystem fs) {
 
   @Override
   public String toString() {
-    return JSON.toJSONString(this, true);
+    StringBuilder sb = new StringBuilder();
+    sb.append("name: ").append(name).append("\n");
+    if (configFile != null) {
+      sb.append("configFile: ").append(configFile).append("\n");
+    }
+    sb.append("packages: ");
+    if (packages == null || packages.length == 0) {
+      sb.append("[]");
+    } else {
+      for (AppMapPackage pkg : packages) {
+        sb.append("\n  - path: ").append(pkg.path);
+        if (pkg.shallow) {
+          sb.append("\n    shallow: true");
+        }
+        if (pkg.exclude != null && pkg.exclude.length > 0) {
+          sb.append("\n    exclude: ").append(Arrays.toString(pkg.exclude));
+        }
+      }
+    }
+    return sb.toString();
   }
 }