Extract SemanticVersion into its own crate (#9956)

This PR extracts the `SemanticVersion` out of `util` and into its own
`SemanticVersion` crate.

This allows for making use of `SemanticVersion` without needing to pull
in some of the heavier dependencies included in the `util` crate.

As part of this the public API for `SemanticVersion` has been tidied up
a bit.

Release Notes:

- N/A

crates/extensions_ui/src/extension_version_selector.rs

@@ -9,9 +9,10 @@ use gpui::{
     prelude::*, AppContext, DismissEvent, EventEmitter, FocusableView, Task, View, WeakView,
 };
 use picker::{Picker, PickerDelegate};
+use semantic_version::SemanticVersion;
 use settings::update_settings_file;
 use ui::{prelude::*, HighlightedLabel, ListItem, ListItemSpacing};
-use util::{ResultExt, SemanticVersion};
+use util::ResultExt;
 use workspace::ModalView;
 
 pub struct ExtensionVersionSelector {