editor: Extract completions and code_actions out of editor.rs

[GoldStrikeArch]

cc @SomeoneToIgnore

Summary

Follow-up to #55352, where the conclusion was to split editor.rs incrementally by topic instead of all at once.

This mechanically extracts two editor topics into focused sibling modules:

• crates/editor/src/code_actions.rs
• crates/editor/src/completions.rs

One odd boundary remains: Editor::context_menu() is still a general context-menu accessor, but it now lives in code_actions.rs because it was part of the moved code actions block and is also used by completions, Vim tests, agent UI, and the quick action bar. Would you prefer that generic context-menu accessor stay in editor.rs for now until context-menu code gets its own extraction?

Testing

• cargo check -p editor --lib
• cargo check -p editor --tests
• cargo check -p editor --lib --features test-support

Self-Review Checklist:

• I've reviewed my own diff for quality, security, and reliability
• Unsafe blocks (if any) have justifying comments
• The content is consistent with the UI/UX checklist
• Tests cover the new/changed behavior
• Performance impact has been considered and is acceptable

Release Notes:

• N/A

[SomeoneToIgnore]

impl Editor are not grouped still; fn and pub(super) fn and maybe others seem to be mixed, not ordered.

[GoldStrikeArch]

@SomeoneToIgnore

impl Editor are not grouped still;

I see. I misunderstood your point, now with the latest changes this:

#[cfg(any(test, feature = "test-support"))]
impl Editor {
// ...
}

Is next to the "main"impl Editor in completions.rs. Is this what you were referring to?

fn and pub(super) fn and maybe others seem to be mixed, not ordered

Right now both "main" impl Editor in code_actions.rs and completions.rs are ordered like this:

• pub fn
• fn
• pub(super) fn

I tried to use the same pattern as in config.rs which we did yesterday. Do you want some other order?

[SomeoneToIgnore]

fn is more private than its surroundings in this case, so the sequence seems odd.
I'd put fn last.

[GoldStrikeArch]

@SomeoneToIgnore

fn is more private than its surroundings in this case, so the sequence seems odd.
I'd put fn last.

Agreed. I moved the fn to the bottom

[SomeoneToIgnore]

Thank you.