Clean up edit predictions settings (#24692)

This PR does some clean up for the edit predictions settings:

- Removed `editor.show_edit_predictions_in_menu`
- Renamed `edit_predictions.inline_preview` to `edit_predictions.mode`

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <agus@zed.dev>

crates/language/src/language.rs

@@ -21,7 +21,7 @@ mod toolchain;
 pub mod buffer_tests;
 pub mod markdown;
 
-pub use crate::language_settings::InlineCompletionPreviewMode;
+pub use crate::language_settings::EditPredictionsMode;
 use crate::language_settings::SoftWrap;
 use anyhow::{anyhow, Context as _, Result};
 use async_trait::async_trait;