Optimize Parse+Describe with TCP Pipelining

[vbergeron]

Second attempt, there I managed to get all the test green locally.

Goal of the PR is to fuse the Parse and the Describe step into one to optimize network exchange.
Despite this being not a very critical workflow, this exchange is simple enough to do a PoC on the concept.

Before:
Parse -> Flush -> await ParseComplete -> Describe -> Flush -> await ParamDesc -> await RowDesc

After:
Parse -> Describe -> Flush -> await ParseComplete -> await ParamDesc -> await RowDesc

This ensure an optimal usage of the socket and should reduce latencies.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.12%. Comparing base (4f40fc9) to head (8e9b8c3).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1059      +/-   ##
==========================================
- Coverage   84.13%   84.12%   -0.01%     
==========================================
  Files         136      137       +1     
  Lines        2099     2098       -1     
  Branches      238      230       -8     
==========================================
- Hits         1766     1765       -1     
  Misses        333      333              

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[mpilquist]

Thanks!