Fairing for internally normalizing request URIs

[jasonyess]

adds a fairing which appends a trailing slash (if needed) to incoming requests, but only for route handlers whose URIs have a trailing slash (so if the route is #[rocket::get("/foo")] the fairing won't do anything)
this fairing will not add a trailing slash if the request is attempting to fetch static files, since it only modifies requests which are trying to reach one of our route handlers

this eliminates the need for some server config and also keeps behavior consistent between both variants, with and without a trailing slash

i found this useful for my local environment so i figured i'll open a pr 🙃 there are a handful of things that point to uris without the trailing slash so this fixes the nuisance

License Acceptance

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 35.55%. Comparing base (3734d28) to head (2086293).

Files with missing lines	Patch %	Lines
pointercrate-core-api/src/normalize_uri.rs	0.00%	26 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #345      +/-   ##
==========================================
- Coverage   35.71%   35.55%   -0.16%     
==========================================
  Files         121      122       +1     
  Lines        5886     5912      +26     
==========================================
  Hits         2102     2102              
- Misses       3784     3810      +26     

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