Initialize pulsar-connectors as standalone repository

Move connectors from pulsar-io/ to top-level directories and set up
standalone Gradle build that consumes Pulsar artifacts as Maven
dependencies.

- Flatten directory structure: pulsar-io/<name>/ -> <name>/
- Add settings.gradle.kts with all connector modules
- Add build.gradle.kts with shared configuration (NAR packaging,
  dependency management, test setup)
- Add gradle/libs.versions.toml with connector-specific dependencies
- Add pulsar-dependencies/ platform module pinning Pulsar versions
- Add distribution/io/ for connector NAR distribution packaging
- Update all cross-project references to new flat paths
- Add .gitignore for build artifacts

Author: merlimat

.gitignore

@@ -0,0 +1,14 @@
+# Gradle
+.gradle/
+build/
+**/build/
+
+# IDE
+.idea/
+*.iml
+.project
+.classpath
+.settings/
+
+# OS
+.DS_Store

pulsar-io/aerospike/build.gradle.kts aerospike/build.gradle.ktspulsar-io/aerospike/build.gradle.kts renamed to aerospike/build.gradle.kts

@@ -21,7 +21,7 @@ plugins {
     alias(libs.plugins.nar)
 }
 dependencies {
-    implementation(project(":pulsar-io:pulsar-io-core"))
+    implementation(libs.pulsar.io.core)
     implementation(libs.jackson.databind)
     implementation(libs.jackson.dataformat.yaml)
     implementation(libs.aerospike.client)

…/io/aerospike/AerospikeAbstractSink.java …/io/aerospike/AerospikeAbstractSink.javapulsar-io/aerospike/src/main/java/org/apache/pulsar/io/aerospike/AerospikeAbstractSink.java renamed to aerospike/src/main/java/org/apache/pulsar/io/aerospike/AerospikeAbstractSink.java pulsar-io/aerospike/src/main/java/org/apache/pulsar/io/aerospike/AerospikeAbstractSink.java renamed to aerospike/src/main/java/org/apache/pulsar/io/aerospike/AerospikeAbstractSink.java

@@ -21,11 +21,11 @@ plugins {
     alias(libs.plugins.nar)
 }
 dependencies {
-    implementation(project(":pulsar-io:pulsar-io-core"))
+    implementation(libs.pulsar.io.core)
     implementation("org.alluxio:alluxio-core-client-fs:2.9.3")
     implementation(libs.jackson.dataformat.yaml)
     implementation(libs.guava)
 
-    testImplementation(project(":pulsar-client-original"))
+    testImplementation(libs.pulsar.client)
     testImplementation("org.alluxio:alluxio-minicluster:2.9.3")
 }