[type:test] Add e2e web socket sync

[wenlongbrother]

1. add webscoket sync script
2. add shenyu-examples-websocket.yml
3. add test case for e2e-websocket
4. add test in github action

Make sure that:

• You have read the contribution guidelines.
• You submit test cases (unit or integration tests) that back your changes.
• Your local test passed ./mvnw clean install -Dmaven.javadoc.skip=true.

[codecov-commenter]

Codecov Report

Merging #5264 (cf670db) into master (adbf042) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #5264      +/-   ##
============================================
- Coverage     61.10%   61.09%   -0.01%     
+ Complexity     8660     8659       -1     
============================================
  Files          1252     1252              
  Lines         38544    38544              
  Branches       3685     3685              
============================================
- Hits          23551    23549       -2     
- Misses        12926    12927       +1     
- Partials       2067     2068       +1     

see 1 file with indirect coverage changes

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[moremind]

lgtm