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/extension/src/extension_manifest.rs

@@ -2,6 +2,7 @@ use anyhow::{anyhow, Context, Result};
 use collections::BTreeMap;
 use fs::Fs;
 use language::LanguageServerName;
+use semantic_version::SemanticVersion;
 use serde::{Deserialize, Serialize};
 use std::{
     ffi::OsStr,
@@ -9,7 +10,6 @@ use std::{
     path::{Path, PathBuf},
     sync::Arc,
 };
-use util::SemanticVersion;
 
 /// This is the old version of the extension manifest, from when it was `extension.json`.
 #[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize)]