Handling of encoded slashes in paths

Both Symfony and Apache are broken by default:

• Apache needs AllowEncodedSlashes=NoDecode, which can't be set in .htaccess. We either need to document it, or a health check that tests how the server performs (the API needs to know what the public URL is)
• Symfony by default decodes "/" for routing, which can be worked around by defining "requirements" = {"identifier" = ".+"},
  • If the route is /<id> it's still broken if you pass "/foo%2Fbar/bla", since the id is foo/bar/bla instead of failing because the route doesn't exist.
  • If there is a route /<id>/bla then the ID is correctly foo/bar at least.

Resources:

• https://httpd.apache.org/docs/current/mod/core.html#allowencodedslashes
• https://github.com/symfony/symfony/issues/13017