Support Priority Work on Connections

[nibanks]

Description

Sometimes an application would like to prefer new work over existing work already queued on the connection. This PR adds the notion of priority to the connection's operation queue, and exposes flags through the API to allow the app to chose to leverage this.

Testing

SpinQuic updated.
Need to add some explicit BVTs.

Documentation

TODO

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 85.22%. Comparing base (bc4454f) to head (1f22fa1).
Report is 2 commits behind head on main.

Files	Patch %	Lines
src/core/api.c	90.90%	2 Missing ⚠️
src/core/connection.c	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4279      +/-   ##
==========================================
+ Coverage   84.23%   85.22%   +0.98%     
==========================================
  Files          56       56              
  Lines       15382    15424      +42     
==========================================
+ Hits        12957    13145     +188     
+ Misses       2425     2279     -146     

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