Include mention context in acp-based native agent (#36006)

Also adds data-layer support for symbols, thread, and rules.

Release Notes:

- N/A

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Co-authored-by: Cole Miller <cole@zed.dev>

crates/acp_thread/Cargo.toml

@@ -34,6 +34,7 @@ settings.workspace = true
 smol.workspace = true
 terminal.workspace = true
 ui.workspace = true
+url.workspace = true
 util.workspace = true
 workspace-hack.workspace = true