Remove egui_web and epi (#1545)

* Remove integration name (it is always eframe)

* Remove egui_web crate

* Move egui_web/CHANGELOG.md into eframe/CHANGELOG.md

* Remove all mentions of egui_web

* Remove epi crate and absorb into eframe

* egui_glow: only use puffin on native

* Remove WASM doc from CI (we don't generate it anyways!)

* Remove eframe::epi and improve eframe docs

eframe/src/native/mod.rs

@@ -1,4 +1,8 @@
 mod epi_integration;
 mod run;
 
+/// File storage which can be used by native backends.
+#[cfg(feature = "persistence")]
+pub mod file_storage;
+
 pub use run::run;