refactor: add read-write lock to ExtensionContextRegistry

[guqing]

What type of PR is this?

/kind improvement
/area core
/area plugin
/milestone 2.8.x

What this PR does / why we need it:

修复由于多线程环境下导致的插件卸载时的路由异常问题

改动描述：
为了确保在多线程环境下访问 ExtensionContextRegistry 类的注册表时的线程安全。通过添加读写锁，可以保证在读取和写入PluginApplicationContext 时只有一个线程可以访问，从而避免了多个线程同时访问注册表时可能出现的竞态条件和数据不一致的问题。同时，更新了 register、remove、getByPluginId、containsContext 和 getPluginApplicationContexts 方法，以在访问注册表时获取和释放适当的锁，从而确保了线程安全。

问题原因：
当插件卸载时，卸载动作在 Reconciler 线程中执行而路由访问是在 reactor 的 NonBlockingThread 线程执行，当 PluginCompositeRouterFunction 的 routerFunctions() 方法从 ExtensionContextRegistry 中获取所有 PluginApplicationContext 并持有还未处理完成时由于 PluginReconciler 中执行了卸载插件逻辑而将某个 PluginApplicationContext 关闭从而让 PluginCompositeRouterFunction 中持有到的对象引用发生变化出现数据不一致问题导致出现 PluginApplicationContext@14971c8e has been closed already 异常。

解决方案：
所以此修改让读取和写入PluginApplicationContext 时只有一个线程可以访问来解决此问题

how to test it?
测试开发模式下卸载插件时是否会出现如 #4242 中所描述的异常信息

Which issue(s) this PR fixes:

Fixes #4242

Does this PR introduce a user-facing change?

修复由于多线程环境下导致的插件卸载时的路由异常问题

[guqing]

/hold 等待 #4241 合并避免重复测试

[codecov]

Codecov Report

Merging #4245 (8b6f8e5) into main (5a0e202) will decrease coverage by 0.07%.
The diff coverage is 66.10%.

@@             Coverage Diff              @@
##               main    #4245      +/-   ##
============================================
- Coverage     60.14%   60.07%   -0.07%     
+ Complexity     2413     2411       -2     
============================================
  Files           366      366              
  Lines         12587    12610      +23     
  Branches        906      906              
============================================
+ Hits           7570     7576       +6     
- Misses         4578     4594      +16     
- Partials        439      440       +1     

Impacted Files	Coverage Δ
...plugin/PluginApplicationEventBridgeDispatcher.java	21.42% <0.00%> (-3.58%)	⬇️
.../halo/app/plugin/PluginApplicationInitializer.java	8.73% <0.00%> (+0.13%)	⬆️
.../run/halo/app/plugin/ExtensionContextRegistry.java	66.66% <59.25%> (+6.66%)	⬆️
...halo/app/plugin/PluginCompositeRouterFunction.java	100.00% <100.00%> (ø)

... and 4 files with indirect coverage changes

[JohnNiang]

/lgtm

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang

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[JohnNiang]

/unhold