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_extras/Cargo.toml

@@ -29,9 +29,6 @@ default = []
 ## Enable [`DatePickerButton`] widget.
 datepicker = ["chrono"]
 
-## Allow serialization using [`serde`](https://docs.rs/serde).
-serde = ["dep:serde"]
-
 ## Support loading svg images.
 svg = ["resvg", "tiny-skia", "usvg"]
 
@@ -42,6 +39,8 @@ tracing = ["dep:tracing", "egui/tracing"]
 [dependencies]
 egui = { version = "0.19.0", path = "../egui", default-features = false }
 
+serde = { version = "1", features = ["derive"] }
+
 #! ### Optional dependencies
 
 # Date operations needed for datepicker widget
@@ -63,9 +62,6 @@ resvg = { version = "0.23", optional = true }
 tiny-skia = { version = "0.6", optional = true } # must be updated in lock-step with resvg
 usvg = { version = "0.23", optional = true }
 
-# feature "serde":
-serde = { version = "1", features = ["derive"], optional = true }
-
 # feature "tracing"
 tracing = { version = "0.1", optional = true, default-features = false, features = [
   "std",