Add system prompt and tool permission to agent2 (#35781)

Release Notes:

- N/A

---------

Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/agent2/Cargo.toml

@@ -16,6 +16,7 @@ acp_thread.workspace = true
 agent-client-protocol.workspace = true
 agent_servers.workspace = true
 anyhow.workspace = true
+assistant_tool.workspace = true
 cloud_llm_client.workspace = true
 collections.workspace = true
 fs.workspace = true
@@ -27,6 +28,7 @@ language_model.workspace = true
 language_models.workspace = true
 log.workspace = true
 project.workspace = true
+prompt_store.workspace = true
 rust-embed.workspace = true
 schemars.workspace = true
 serde.workspace = true
@@ -36,6 +38,7 @@ smol.workspace = true
 ui.workspace = true
 util.workspace = true
 uuid.workspace = true
+watch.workspace = true
 worktree.workspace = true
 workspace-hack.workspace = true
 
@@ -47,6 +50,7 @@ env_logger.workspace = true
 fs = { workspace = true, "features" = ["test-support"] }
 gpui = { workspace = true, "features" = ["test-support"] }
 gpui_tokio.workspace = true
+language = { workspace = true, "features" = ["test-support"] }
 language_model = { workspace = true, "features" = ["test-support"] }
 project = { workspace = true, "features" = ["test-support"] }
 reqwest_client.workspace = true