editoast: add operator =i for case insensitive "strict" equality

[leovalais]

["=i", "tot", "ToT"]
# but not
["=i", "tot", "toto"] # differs from search

Useful for OP search as we want trigram strict equality, but we don't want to bother about the case (otherwise the front would need to known about DB internals).

[codecov]

Codecov Report

Merging #3275 (5074210) into dev (3dbd563) will decrease coverage by 0.01%.
The diff coverage is 80.00%.

❗ Current head 5074210 differs from pull request most recent head 1257660. Consider uploading reports for the commit 1257660 to get more accurate results

@@             Coverage Diff              @@
##                dev    #3275      +/-   ##
============================================
- Coverage     40.36%   40.36%   -0.01%     
  Complexity     1711     1711              
============================================
  Files           630      630              
  Lines         18752    18753       +1     
  Branches       2342     2342              
============================================
  Hits           7570     7570              
- Misses        10780    10781       +1     
  Partials        402      402              

Flag	Coverage Δ
editoast	71.31% <80.00%> (-0.03%)	⬇️

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

Impacted Files	Coverage Δ
editoast/src/views/search/process.rs	92.20% <66.66%> (ø)
editoast/src/views/search/context.rs	83.63% <100.00%> (+0.30%)	⬆️
editoast/src/generated_data/utils.rs	78.94% <0.00%> (-5.27%)	⬇️
editoast/src/map/bounding_box.rs	19.38% <0.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[flomonster]

LGTM. Can you amend your last commit?