Migrate keymap and settings + edit predictions rename (#23834)

- [x] snake case keymap properties
- [x] flatten actions
- [x] keymap migration + notfication
- [x] settings migration + notification
- [x] inline completions -> edit predictions 

### future: 
- keymap notification doesn't show up on start up, only on keymap save.
this is existing bug in zed, will be addressed in seperate PR.

Release Notes:

- Added a notification for deprecated settings and keymaps, allowing you
to migrate them with a single click. A backup of your existing keymap
and settings will be created in your home directory.
- Modified some keymap actions and settings for consistency.

---------

Co-authored-by: Piotr Osiewicz <piotr@zed.dev>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/vim/src/state.rs

@@ -10,7 +10,6 @@ use gpui::{
     Action, App, BorrowAppContext, ClipboardEntry, ClipboardItem, Entity, Global, WeakEntity,
 };
 use language::Point;
-use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 use settings::{Settings, SettingsStore};
 use std::borrow::BorrowMut;
@@ -18,7 +17,7 @@ use std::{fmt::Display, ops::Range, sync::Arc};
 use ui::{Context, SharedString};
 use workspace::searchable::Direction;
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Deserialize, JsonSchema, Serialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
 pub enum Mode {
     Normal,
     Insert,
@@ -59,7 +58,7 @@ impl Default for Mode {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Deserialize, JsonSchema)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum Operator {
     Change,
     Delete,
@@ -82,7 +81,6 @@ pub enum Operator {
     },
     AddSurrounds {
         // Typically no need to configure this as `SendKeystrokes` can be used - see #23088.
-        #[serde(skip)]
         target: Option<SurroundsType>,
     },
     ChangeSurrounds {