Remove 2 suffix from gpui_macros, fix compile errors in tests

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/gpui_macros/src/derive_into_element.rs

@@ -0,0 +1,27 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, DeriveInput};
+
+pub fn derive_into_element(input: TokenStream) -> TokenStream {
+    let ast = parse_macro_input!(input as DeriveInput);
+    let type_name = &ast.ident;
+    let (impl_generics, type_generics, where_clause) = ast.generics.split_for_impl();
+
+    let gen = quote! {
+        impl #impl_generics gpui::IntoElement for #type_name #type_generics
+        #where_clause
+        {
+            type Element = gpui::Component<Self>;
+
+            fn element_id(&self) -> Option<gpui::ElementId> {
+                None
+            }
+
+            fn into_element(self) -> Self::Element {
+                gpui::Component::new(self)
+            }
+        }
+    };
+
+    gen.into()
+}