editoast: enhance error logging

[leovalais]

Makes it easier to spot where an error originates just by looking at the logs (e.g.: DieselError)

[codecov]

Codecov Report

Merging #4815 (2394306) into dev (13e1ab5) will increase coverage by 0.00%.
Report is 9 commits behind head on dev.
The diff coverage is 40.90%.

@@            Coverage Diff            @@
##                dev    #4815   +/-   ##
=========================================
  Coverage     21.80%   21.81%           
  Complexity     2248     2248           
=========================================
  Files           861      861           
  Lines         90299    90321   +22     
  Branches       2284     2284           
=========================================
+ Hits          19693    19703   +10     
- Misses        69345    69357   +12     
  Partials       1261     1261           

Flag	Coverage Δ
editoast	70.95% <40.90%> (-0.09%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
editoast/src/client/mod.rs	100.00% <ø> (ø)
editoast/src/main.rs	9.34% <0.00%> (-0.21%)	⬇️
editoast/src/error.rs	26.66% <25.00%> (+1.66%)	⬆️
editoast/src/core/mod.rs	44.68% <57.14%> (+2.18%)	⬆️

... and 2 files with indirect coverage changes

[flomonster]

LGTM