Break out plotting to own crate egui_plot (#3282)

This replaces `egui::plot` with the new crate `egui_plot`

crates/egui_plot/Cargo.toml

@@ -0,0 +1,42 @@
+[package]
+name = "egui_plot"
+version = "0.22.0"
+authors = [
+  "Dominik Rössler <dominik@freshx.de>",
+  "Emil Ernerfeldt <emil.ernerfeldt@gmail.com>",
+  "René Rössler <rene@freshx.de>",
+]
+description = "Immediate mode plotting for the egui GUI library"
+edition = "2021"
+rust-version = "1.67"
+homepage = "https://github.com/emilk/egui"
+license = "MIT OR Apache-2.0"
+readme = "README.md"
+repository = "https://github.com/emilk/egui"
+categories = ["visualization", "gui"]
+keywords = ["egui", "plot", "plotting"]
+include = ["../LICENSE-APACHE", "../LICENSE-MIT", "**/*.rs", "Cargo.toml"]
+
+[package.metadata.docs.rs]
+all-features = true
+
+[lib]
+
+
+[features]
+default = []
+
+
+## Allow serialization using [`serde`](https://docs.rs/serde).
+serde = ["dep:serde", "egui/serde"]
+
+
+[dependencies]
+egui = { version = "0.22.0", path = "../egui", default-features = false }
+
+
+#! ### Optional dependencies
+## Enable this when generating docs.
+document-features = { version = "0.2", optional = true }
+
+serde = { version = "1", optional = true, features = ["derive"] }