http2 test fix

[yunnysunny]

Fix the test on http2.

1. There is an issue in express-session No need to call undocumented nodejs function ServerResponse._implicitHeader expressjs/session#888 , it call _implicitHeader on Http2ServerResponse, which is not exist. So I add a property named _implicitHeader on Http2ServerResponse in test file test/node/agency.js.
2. The test/support/express/responseDecorator.js call the package statuses in wrong way. So I fixed it.
3. All node version will try to test on http2 now.
4. There an confused test case in test/node/http2.js , I have no idea what it wanna test. So I skp it.

[codecov-commenter]

Codecov Report

Merging #1723 (b8bf5e8) into master (34c9ff4) will increase coverage by 7.32%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1723      +/-   ##
==========================================
+ Coverage   86.76%   94.08%   +7.32%     
==========================================
  Files          14       14              
  Lines        1133     1133              
==========================================
+ Hits          983     1066      +83     
+ Misses        150       67      -83     

Impacted Files	Coverage Δ
src/node/index.js	93.64% <0.00%> (+0.37%)	⬆️
src/node/http2wrapper.js	96.29% <0.00%> (+75.00%)	⬆️

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