Fix edit prediction disablement with "disable_ai": true setting (#35513)

Even after #35327 edit predictions were still being queried and shown
after setting `"disable_ai": true`

Also moves `DisableAiSettings` to the `project` crate so that it gets
included in tests via existing use of `Project::init_settings(cx)`.

Release Notes:

- Fixed `"disable_ai": true` setting disabling edit predictions.

crates/agent_ui/src/agent_ui.rs

@@ -31,7 +31,7 @@ use std::sync::Arc;
 use agent::{Thread, ThreadId};
 use agent_settings::{AgentProfileId, AgentSettings, LanguageModelSelection};
 use assistant_slash_command::SlashCommandRegistry;
-use client::{Client, DisableAiSettings};
+use client::Client;
 use command_palette_hooks::CommandPaletteFilter;
 use feature_flags::FeatureFlagAppExt as _;
 use fs::Fs;
@@ -40,6 +40,7 @@ use language::LanguageRegistry;
 use language_model::{
     ConfiguredModel, LanguageModel, LanguageModelId, LanguageModelProviderId, LanguageModelRegistry,
 };
+use project::DisableAiSettings;
 use prompt_store::PromptBuilder;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};