internal: implement path normalization w/ configurable rules

Strips query strings and URL fragmenets, prevents unbounded Prometheus
metrics by normalizing paths like:

- `/users/12345/profile -> /users/:id/profile`
- `/page?utm_source=twitter -> /page`
- `/a/../b -> /b`

etc.

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I72f2fa2452f4666567143d052b5716476a6a6964

testdata/config.valid.yaml

@@ -14,6 +14,7 @@ site:
     strip_fragment: true
     collapse_numeric_segments: true
     max_segments: 5
+    normalize_trailing_slash: true
 
 limits:
   max_paths: 1000