T20: Debug

- DebugToolbar, BreakpointList, CallStack with folded library frames, ThreadList
- VariablesPanel and WatchPanel, colored by kind, changes washed
- HexViewer at a base address with the byte under the pointer lit on both sides
- Disassembly with source lines, registers and numbers colored, gutter breakpoints
- Flamegraph that zooms by frame, TimelineProfiler that zooms and pans by wheel
- NetworkInspector with a waterfall, a filter and a request's headers and body
- icons: redo-dot, arrow-down-to-dot, arrow-up-from-dot
- gallery: the Debug page

src/debug/mod.rs

@@ -0,0 +1,24 @@
+use std::rc::Rc;
+
+use gpui::{App, Window};
+
+mod disasm;
+mod flame;
+mod hex;
+mod network;
+mod session;
+mod stack;
+mod timeline;
+mod variables;
+
+pub use disasm::{Disassembly, Instruction};
+pub use flame::{Flamegraph, Placed, ProfileFrame, place};
+pub use hex::HexViewer;
+pub use network::{NetworkInspector, Request};
+pub use session::{Breakpoint, BreakpointList, DebugCommand, DebugState, DebugToolbar};
+pub use stack::{CallStack, StackFrame, Thread, ThreadList, ThreadState};
+pub use timeline::{Span, TimelineProfiler, zoomed};
+pub use variables::{ValueKind, Variable, VariablesPanel, Watch, WatchPanel};
+
+/// Tells the owner which row, by index.
+type OnIndex = Rc<dyn Fn(usize, &mut Window, &mut App)>;