Add egui_extras dependency

Adds `egui_extras` to Cargo.toml and Cargo.lock to enable enhanced table
widgets.
Also introduces a new `StateTab` enum and integrates the
`egui_extras::TableBuilder` to display global variables in a structured
table within the application's state panel. This enhances the debugging
and introspection capabilities of the compiler UI by providing a clear
view of the environment's global state.

examples/data_stream_pipe_series.myc

@@ -9,7 +9,7 @@
     (fn [eu ge]
       (do
         (def dax (.close (ge 0)))
-        (def eur (- dax (ge 1)))
+        (def eur (- dax (.close (ge 1))))
         (print cnt ": dax=" eur " (" (/ eur (.close (eu 0))) "$)" )
         (assign cnt (+ cnt 1))
       )