fix(api): missing trailing / route for environment-document

[Totodore]

Each route was duplicated manually to work with trailing slash. However the /environment-document path was not. And the Rust SDK use /environment-document/ leading to 404.

Fix this by using the NormalizePathLayer rather than duplicating the routes which is error prone.

Side notes

Error message in the rust SDK are particularly not helpful: Failed to update environment: Flagsmith API error: . Will retry on next interval.. I will open a PR later to fix this.

Don't hesitate if this need any change.

[emyller]

LGTM — thanks for the contribution!

[emyller]

Sorry for taking my previous approval back. Would you think it makes sense to ensure the intended behaviour in tests?

[Totodore]

I don't really see the point because the behavior is automatically standardized for every endpoints with the NormalizeLayer. The test would only cover an accidental removal of the layer which is likely unprobable.
If you insist I can definitely add tests, as you want.

[gagantrivedi]

err.. looks like this is breaking our tests — middleware added with Router::layer runs after routing, so the normalize layer never sees the trailing slash. We probably need to wrap the layer around the whole router instead? https://docs.rs/axum/latest/axum/middleware/index.html#rewriting-request-uri-in-middleware