Extract paths out of util (#13182)

This PR extracts the definition of the various Zed paths out of `util`
and into a new `paths` crate.

`util` is for generic utils, while these paths are Zed-specific. For
instance, `gpui` depends on `util`, and it shouldn't have knowledge of
these paths, since they are only used by Zed.

Release Notes:

- N/A

crates/assistant/src/prompt_library.rs

@@ -20,6 +20,7 @@ use gpui::{
 use heed::{types::SerdeBincode, Database, RoTxn};
 use language::{language_settings::SoftWrap, Buffer, LanguageRegistry};
 use parking_lot::RwLock;
+use paths::PROMPTS_DIR;
 use picker::{Picker, PickerDelegate};
 use rope::Rope;
 use serde::{Deserialize, Serialize};
@@ -36,7 +37,7 @@ use ui::{
     div, prelude::*, IconButtonShape, ListItem, ListItemSpacing, ParentElement, Render,
     SharedString, Styled, TitleBar, Tooltip, ViewContext, VisualContext,
 };
-use util::{paths::PROMPTS_DIR, ResultExt, TryFutureExt};
+use util::{ResultExt, TryFutureExt};
 use uuid::Uuid;
 use workspace::Workspace;