Add support for publishing events among plugins

[JohnNiang]

What type of PR is this?

/kind feature
/area core
/area plugin

What this PR does / why we need it:

This PR enhance usage of SharedEvent annotation to add support for publishing events among plugins.

How to test?

1. Clone repository https://github.com/halo-dev/plugin-starter

2. Change build.gradle as following:

   dependencies {
       implementation platform('run.halo.tools.platform:plugin:2.17.0-SNAPSHOT')

3. Change StarterPlugin as following:

   @Component
   public class StarterPlugin extends BasePlugin {
   
       private final ApplicationContext appContext;
   
       public StarterPlugin(PluginContext pluginContext, ApplicationContext appContext) {
           super(pluginContext);
           this.appContext = appContext;
       }
   
       @Override
       public void start() {
           appContext.publishEvent(new PostDeletedEvent(this, "fake-plugin"));
       }
   
       @Override
       public void stop() {
       }
   
       @EventListener(PostDeletedEvent.class)
       public void onApplicationEvent(PostDeletedEvent event) {
           System.out.println("Post deleted event received in plugin: " + event.getName());
       }
   }

4. Add a listener to Halo core

	    @EventListener(PostDeletedEvent.class)
	    public void onApplicationEvent(PostDeletedEvent event) {
	        System.out.println("Post deleted event received in core: " + event.getName());
	    }

5. Build plugin and install plugin
6. Enable the plugin and see the result

Does this PR introduce a user-facing change?

为插件提供发送共享事件的支持。

[codecov]

Codecov Report

Attention: Patch coverage is 47.16981% with 28 lines in your changes missing coverage. Please review.

Project coverage is 56.48%. Comparing base (5fdf6c0) to head (495d3db).
Report is 238 commits behind head on main.

Files	Patch %	Lines
.../run/halo/app/plugin/PluginApplicationContext.java	0.00%	12 Missing ⚠️
...un/halo/app/plugin/PluginSharedEventDelegator.java	36.36%	7 Missing ⚠️
.../run/halo/app/plugin/HaloSharedEventDelegator.java	45.45%	4 Missing and 2 partials ⚠️
...plugin/DefaultPluginApplicationContextFactory.java	0.00%	2 Missing ⚠️
...ava/run/halo/app/plugin/SharedEventDispatcher.java	94.11%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6081      +/-   ##
============================================
- Coverage     56.91%   56.48%   -0.43%     
- Complexity     3319     3549     +230     
============================================
  Files           587      625      +38     
  Lines         18968    20981    +2013     
  Branches       1401     1484      +83     
============================================
+ Hits          10795    11852    +1057     
- Misses         7594     8527     +933     
- Partials        579      602      +23     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.2% Duplication on New Code

See analysis details on SonarCloud

[ruibaby]

@JohnNiang 是否需要补充一下插件开发的文档？

[JohnNiang]

@JohnNiang 是否需要补充一下插件开发的文档？

目前确实缺少相关的文档，稍后我完善一下。

[ruibaby]

提个 PR 到 halo-dev/docs 吧。

8c40bf4#diff-b8447709f93eeedfadb44f95a9c5fd9f508c8a48c446b9df0f5022722df2992d

[ruibaby]

/lgtm

[guqing]

/approve

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: guqing

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