[wip] add basic read only mode to connect

[jenshnielsen]

If we go this way there are a bunch of TODOs

• [ ] Make sure this has good error messages
• [ ] Expose to higher level api where it makes sense
• [ ] Tests

[codecov[bot]]

Codecov Report

Merging #4783 (653d700) into master (7da102b) will decrease coverage by 0.90%. The diff coverage is 80.00%.

@@            Coverage Diff             @@
##           master    #4783      +/-   ##
==========================================
- Coverage   68.20%   67.29%   -0.91%     
==========================================
  Files         339      339              
  Lines       32019    32046      +27     
==========================================
- Hits        21837    21565     -272     
- Misses      10182    10481     +299