Rename SharedUrl to SharedUri (#7084)

This PR renames `SharedUrl` to `SharedUri` to better reflect its intent.

I'm still not entirely happy with this naming, as the file paths that we
can store in here are not _really_ URIs, as they are lacking a protocol.

I want to explore changing `SharedUri` / `SharedUrl` back to alway
storing a URL and treat local filepaths differently, as it seems we're
conflating two different concerns under the same umbrella, at the
moment.

Release Notes:

- N/A

crates/collab_ui/src/chat_panel.rs

@@ -714,7 +714,7 @@ fn format_timestamp(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use gpui::{HighlightStyle, SharedUrl};
+    use gpui::{HighlightStyle, SharedUri};
     use pretty_assertions::assert_eq;
     use rich_text::Highlight;
     use time::{Date, OffsetDateTime, Time, UtcOffset};
@@ -730,7 +730,7 @@ mod tests {
             timestamp: OffsetDateTime::now_utc(),
             sender: Arc::new(client::User {
                 github_login: "fgh".into(),
-                avatar_uri: SharedUrl::network("avatar_fgh"),
+                avatar_uri: SharedUri::network("avatar_fgh"),
                 id: 103,
             }),
             nonce: 5,