Refactor agent packaging and class loader

[taojintianxia]

Fixes #23392.

Changes proposed in this pull request:

• Refactor agent packaging and class loader

---

Before committing this PR, I'm sure that I have checked the following options:

• My code follows the code of conduct of this project.
• I have self-reviewed the commit code.
• I have (or in comment I request) added corresponding labels for the pull request.
• I have passed maven check locally : ./mvnw clean install -B -T1C -Dmaven.javadoc.skip -Dmaven.jacoco.skip -e.
• I have made corresponding changes to the documentation.
• I have added corresponding unit tests for my changes.

[codecov-commenter]

Codecov Report

Merging #23436 (82cede2) into master (51bf80f) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##             master   #23436   +/-   ##
=========================================
  Coverage     49.87%   49.87%           
  Complexity     2461     2461           
=========================================
  Files          4081     4081           
  Lines         58314    58312    -2     
  Branches       9262     9261    -1     
=========================================
  Hits          29085    29085           
+ Misses        26669    26667    -2     
  Partials       2560     2560           

Impacted Files	Coverage Δ
...gsphere/agent/core/plugin/jar/PluginJarLoader.java	0.00% <0.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more