Rework error representation (#517)

* start error repr rework

* add kitsune-error crate

* progress

* rm unused dependencies

* progress

* progress

* progress

* progress

* finish

* fix checks

* fix tests

* enable serde for garde

* Add codecov token

* remove some more error enums

* remove another enum

* remove httperror

* improve somewhat

* make it possible to return responses as the 'body'

* use try-block polyfills everywhere

.github/workflows/coverage.yml

@@ -48,7 +48,8 @@ jobs:
           DATABASE_URL: "postgres://postgres:postgres@localhost/test_db"
           REDIS_URL: "redis://localhost"
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           files: lcov.info
           fail_ci_if_error: true
+          token: ${{ secrets.CODECOV_TOKEN }}