build(all): 项目结构优化

优化整体项目结构，优化Javadoc生成方式与部署方式。

extension/papi/pom.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>easyplugin-parent</artifactId>
+        <groupId>cc.carm.lib</groupId>
+        <version>1.4.0</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <properties>
+        <maven.compiler.source>${project.jdk.version}</maven.compiler.source>
+        <maven.compiler.target>${project.jdk.version}</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.encoding>UTF-8</maven.compiler.encoding>
+    </properties>
+
+    <artifactId>easyplugin-placeholderapi</artifactId>
+    <packaging>jar</packaging>
+
+    <name>EasyPlugin-PlaceholderAPI</name>
+
+</project>