chore(codersdk): deprecate WorkspaceAppStatus.{NeedsUserAttention,Icon} (#17358)

https://github.com/coder/coder/pull/17163 introduced the
`workspace_app_statuses` table. Two of these fields
(`needs_user_attention`, `icon`) turned out to be surplus to
requirements.

- Removes columns `needs_user_attention` and `icon` from
`workspace_app_statuses`
- Marks the corresponding fields of `codersdk.WorkspaceAppStatus` as
deprecated.

coderd/workspaceagents.go

@@ -366,11 +366,6 @@ func (api *API) patchWorkspaceAgentAppStatus(rw http.ResponseWriter, r *http.Req
 			String: req.URI,
 			Valid:  req.URI != "",
 		},
-		Icon: sql.NullString{
-			String: req.Icon,
-			Valid:  req.Icon != "",
-		},
-		NeedsUserAttention: req.NeedsUserAttention,
 	})
 	if err != nil {
 		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{