Require alt-tab for AcceptEditPrediction when tab inserting whitespace is desired (#24705)

Moves tab whitespace insertion logic out of `AcceptEditPrediction`
handler.

`edit_prediction_requires_modifier` context will now be true when on a
line with leading whitespace, so that `alt-tab` is used to accept
predictions in this case. This way leading indentation can be typed when
edit predictions are visible

Release Notes:

- N/A

Co-authored-by: Ben <ben@zed.dev>
Co-authored-by: Joao <joao@zed.dev>

crates/editor/src/inline_completion_tests.rs

@@ -1,10 +1,9 @@
 use gpui::{prelude::*, Entity};
 use indoc::indoc;
 use inline_completion::EditPredictionProvider;
-use language::{Language, LanguageConfig};
 use multi_buffer::{Anchor, MultiBufferSnapshot, ToPoint};
 use project::Project;
-use std::{num::NonZeroU32, ops::Range, sync::Arc};
+use std::ops::Range;
 use text::{Point, ToOffset};
 
 use crate::{
@@ -124,54 +123,6 @@ async fn test_inline_completion_jump_button(cx: &mut gpui::TestAppContext) {
     "});
 }
 
-#[gpui::test]
-async fn test_indentation(cx: &mut gpui::TestAppContext) {
-    init_test(cx, |settings| {
-        settings.defaults.tab_size = NonZeroU32::new(4)
-    });
-
-    let language = Arc::new(
-        Language::new(
-            LanguageConfig::default(),
-            Some(tree_sitter_rust::LANGUAGE.into()),
-        )
-        .with_indents_query(r#"(_ "(" ")" @end) @indent"#)
-        .unwrap(),
-    );
-
-    let mut cx = EditorTestContext::new(cx).await;
-    cx.update_buffer(|buffer, cx| buffer.set_language(Some(language), cx));
-    let provider = cx.new(|_| FakeInlineCompletionProvider::default());
-    assign_editor_completion_provider(provider.clone(), &mut cx);
-
-    cx.set_state(indoc! {"
-        const a: A = (
-        ˇ
-        );
-    "});
-
-    propose_edits(
-        &provider,
-        vec![(Point::new(1, 0)..Point::new(1, 0), "    const function()")],
-        &mut cx,
-    );
-    cx.update_editor(|editor, window, cx| editor.update_visible_inline_completion(window, cx));
-
-    assert_editor_active_edit_completion(&mut cx, |_, edits| {
-        assert_eq!(edits.len(), 1);
-        assert_eq!(edits[0].1.as_str(), "    const function()");
-    });
-
-    // When the cursor is before the suggested indentation level, accepting a
-    // completion should just indent.
-    accept_completion(&mut cx);
-    cx.assert_editor_state(indoc! {"
-        const a: A = (
-            ˇ
-        );
-    "});
-}
-
 #[gpui::test]
 async fn test_inline_completion_invalidation_range(cx: &mut gpui::TestAppContext) {
     init_test(cx, |_| {});