Add new Button and IconButton components (#3448)

This PR adds new `Button` and `IconButton` components built on top of
our new button abstractions.

Both of these buttons are built from the common `ButtonLike` base, and
implement the `ButtonCommon` (name TBD) trait in order to provide a
common interface.

There are still some visual tweaks that we'll need to make to the new
buttons, but those should be straightforward to make after we land this.

Release Notes:

- N/A

crates/editor2/src/editor.rs

@@ -99,7 +99,8 @@ use text::{OffsetUtf16, Rope};
 use theme::{
     ActiveTheme, DiagnosticStyle, PlayerColor, SyntaxTheme, Theme, ThemeColors, ThemeSettings,
 };
-use ui::{h_stack, v_stack, HighlightedLabel, IconButton, Popover, StyledExt, Tooltip};
+use ui::prelude::*;
+use ui::{h_stack, v_stack, HighlightedLabel, IconButton, Popover, Tooltip};
 use util::{post_inc, RangeExt, ResultExt, TryFutureExt};
 use workspace::{
     item::{ItemEvent, ItemHandle},
@@ -4391,7 +4392,7 @@ impl Editor {
                                         editor.fold_at(&FoldAt { buffer_row }, cx);
                                     }
                                 }))
-                                .color(ui::Color::Muted)
+                                .icon_color(ui::Color::Muted)
                         })
                     })
                     .flatten()

crates/editor2/src/element.rs

@@ -48,6 +48,7 @@ use std::{
 };
 use sum_tree::Bias;
 use theme::{ActiveTheme, PlayerColor};
+use ui::prelude::*;
 use ui::{h_stack, IconButton, Tooltip};
 use util::ResultExt;
 use workspace::item::Item;