egui_extras::Table improvements (#2369)

* Use simple `ui.interact` for the resize line

* Introduce TableReizeState

* Simplify some code

* Add striped options to table demo

* Auto-size table columns by double-clicking the resize line

* Table: add option to auto-size the columns

* Table: don't let column width gets too small, unless clipping is on

* egui_extras: always use serde

Otherwise using `get_persisted` etc is impossible,
and working around that tedious.

* Avoid clipping last column in a resizable table

* Some better naming

* Table: Use new `Column` for setting column sizes and properties

Also make `clip` a per-column property

* All Table:s store state for auto-sizing purposes

* Customize each column wether or not it is resizable

* fix some auto-sizing bugs

* Fix shrinkage of adaptive column content

* Rename `scroll` to `vscroll` for clarity

* Add Table::scroll_to_row

* scroll_to_row takes alignment

* Fix bug in table sizing

* Strip: turn clipping OFF by default, because it is dangerous and sucks

* Add TableBody::mac_rect helper

* Table: add options to control the scroll area height.

* Docstring fixes

* Cleanup

crates/egui_demo_app/Cargo.toml

@@ -20,8 +20,8 @@ default = ["glow", "persistence"]
 
 http = ["ehttp", "image", "poll-promise", "egui_extras/image"]
 persistence = ["eframe/persistence", "egui/persistence", "serde"]
-screen_reader = ["eframe/screen_reader"]                                        # experimental
-serde = ["dep:serde", "egui_demo_lib/serde", "egui_extras/serde", "egui/serde"]
+screen_reader = ["eframe/screen_reader"]                          # experimental
+serde = ["dep:serde", "egui_demo_lib/serde", "egui/serde"]
 syntax_highlighting = ["egui_demo_lib/syntax_highlighting"]
 
 glow = ["eframe/glow"]