Pull Request Overview

This PR adds a new append_path() method to the Url type through an extension trait, providing a convenient way to append path segments to URLs while handling slash normalization and preserving query parameters.

• Introduces UrlExt trait with append_path() method for intelligent URL path manipulation
• Implements slash handling logic to avoid double slashes or missing separators
• Adds comprehensive test coverage for various URL and path combinations

Revert "overwrite if new path starts with slash"

Better, but can be more efficient for now (see code suggestion). Before we GA, we should actually look at splitting a path in TypeSpec and building up segments more efficiently using Url::path_segments_mut(). We can then in the emitter efficiently add fixed string segments like "containers" and just append variables to be replaced with the name instead of a String::replace which is terribly inefficient to do repeatedly. The String grows more often and by smaller amounts than probably necessary if more is known up front.

In some code we'll run in tight loops like with Storage Blobs, we're going to be building up endpoints quickly in a tight loop so we'll want to optimize where we can. We can always get better, though, so this doesn't haven't to be perfect. I'd just consider my suggestion below. IMO, it's more intuitive and certainly has fewer allocations. You're will have at least 2 but likely more.