Migrate to express 5 (#7572)

Main changes:
- type checker cares about the return value (`void`) of handlers, so no
more `return res.send("...")` as that returns `express` type.
- regexes on slugs no longer supported, but we weren't really using them
in any meaningful way. The two places that had to be updated:
- `/clientstate/:clientstate64` - now uses a regex directly and tests added (thanks @partouf for spotting #4844)
- `/bits/:bits.html` - was some `\w+` but I believe that's unnecessary
for the same reasons
- actually call the Sentry handler. I don't know if this actually worked
before but the API checks suggest not.

package.json

@@ -40,7 +40,7 @@
     "cross-env": "^7.0.3",
     "enhanced-ms": "^4.1.0",
     "events": "^3.3.0",
-    "express": "^4.21.2",
+    "express": "^5.1.0",
     "file-saver": "^2.0.5",
     "golden-layout": "^1.5.9",
     "http-proxy": "^1.18.1",
@@ -91,7 +91,7 @@
     "@types/bootstrap": "^5.2.10",
     "@types/chai": "^5.2.1",
     "@types/compression": "^1.7.5",
-    "@types/express": "^4.17.21",
+    "@types/express": "^5.0.1",
     "@types/file-saver": "^2.0.7",
     "@types/http-proxy": "^1.17.16",
     "@types/jquery": "^3.5.32",