make HTTPClient public ~Copyable

[swhitty]

Make the private spa _HTTPClient public, and ~Copyable allowing it stream responses closing the socket when done.

resolves #216

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.91%. Comparing base (5364faa) to head (00624f4).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #225      +/-   ##
==========================================
- Coverage   92.91%   92.91%   -0.01%     
==========================================
  Files          71       71              
  Lines        3728     3727       -1     
==========================================
- Hits         3464     3463       -1     
  Misses        264      264              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.