add :edit and :e as aliases for :open (#11186)

Vim supports these, and i can't think of any reason helix would want to have a different meaning for `:edit` than `:open`.

docs: https://vimhelp.org/editing.txt.html#%3Aedit

helix-term/src/commands/typed.rs

@@ -2537,7 +2537,7 @@ fn read(cx: &mut compositor::Context, args: &[Cow<str>], event: PromptEvent) ->
     },
     TypableCommand {
         name: "open",
-        aliases: &["o"],
+        aliases: &["o", "edit", "e"],
         doc: "Open a file from disk into the current view.",
         fun: open,
         signature: CommandSignature::all(completers::filename),