Tooling · Inspection: inspector, FPS meter, render counter and event logger

install_inspector draws gpui's debug inspector in Ely's look: a panel
with the picked box's source, ids and box model, and its margin,
border, padding and size drawn over the page through raise, since the
panel scrolls. FpsMeter counts frames on the executor's clock and
colors each by the frames it missed. RenderCounter counts the renders
of the view that draws it. EventLogger lists the input that reaches
what it holds, its canvas laid first so a child's stop hides nothing.

src/tooling/mod.rs

@@ -1,5 +1,15 @@
+mod events;
+#[cfg(debug_assertions)]
+mod inspector;
+mod perf;
 mod playground;
+mod renders;
 #[cfg(all(test, feature = "test-support"))]
 mod tests;
 
+pub use events::EventLogger;
+#[cfg(debug_assertions)]
+pub use inspector::install_inspector;
+pub use perf::FpsMeter;
 pub use playground::{Knob, Playground, Setting, Settings};
+pub use renders::RenderCounter;