fix: Refactor MCP Server into MCP Session and MCP Server

[Jing-ze]

Ⅰ. Describe what this PR did

Refactor MCP Server into MCP Session and MCP Server
Support refresh TTL in each get config request

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 44.98%. Comparing base (ef31e09) to head (7405efb).
Report is 465 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2120      +/-   ##
==========================================
+ Coverage   35.91%   44.98%   +9.07%     
==========================================
  Files          69       79      +10     
  Lines       11576    12811    +1235     
==========================================
+ Hits         4157     5763    +1606     
+ Misses       7104     6700     -404     
- Partials      315      348      +33     

Files with missing lines	Coverage Δ
pkg/ingress/kube/configmap/mcp_server.go	92.35% <100.00%> (ø)

... and 74 files with indirect coverage changes

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[johnlanni]

This dependency should be replaced with: https://github.com/higress-group/envoy