language: Add LanguageName::new_static to reduce allocations (#44380)

Implements a specialized constructor `LanguageName::new_static` for
`&'static str` which reduces allocations.

`LanguageName::new` always backs the underlying `SharedString` with an
owned `Arc<str>` even when a `&'static str` is passed. This makes us
allocate each time we create a new `LanguageName` no matter what.
Creating a specialized constructor for `&'static str` allows us to
essentially construct them for free.

Additional change:
Encourages using explicit constructors to avoid needless allocations.
Currently there were no instances of this trait being called where the
lifetime was not `'static` saving another 48 locations of allocation.

```rust
impl<'a> From<&'a str> for LanguageName {
    fn from(str: &'a str) -> Self {
        Self(SharedString::new(str))
    }
}

// to 

impl From<&'static str> for LanguageName {
    fn from(str: &'static str) -> Self {
        Self(SharedString::new_static(str))
    }
}

```

Release Notes:

- N/A

crates/project/src/project_tests.rs

@@ -746,7 +746,7 @@ async fn test_running_multiple_instances_of_a_single_server_in_one_worktree(
                     worktree_id,
                     path: rel_path("project-b/source_file.py").into(),
                 },
-                LanguageName::new("Python"),
+                LanguageName::new_static("Python"),
                 cx,
             )
         })
@@ -762,7 +762,7 @@ async fn test_running_multiple_instances_of_a_single_server_in_one_worktree(
                     worktree_id,
                     path: rel_path("project-b/source_file.py").into(),
                 },
-                LanguageName::new("Python"),
+                LanguageName::new_static("Python"),
                 cx,
             )
         })

crates/project/src/terminals.rs

@@ -111,7 +111,7 @@ impl Project {
             );
         let toolchains = project_path_contexts
             .filter(|_| detect_venv)
-            .map(|p| self.active_toolchain(p, LanguageName::new("Python"), cx))
+            .map(|p| self.active_toolchain(p, LanguageName::new_static("Python"), cx))
             .collect::<Vec<_>>();
         let lang_registry = self.languages.clone();
         cx.spawn(async move |project, cx| {
@@ -311,7 +311,7 @@ impl Project {
             );
         let toolchains = project_path_contexts
             .filter(|_| detect_venv)
-            .map(|p| self.active_toolchain(p, LanguageName::new("Python"), cx))
+            .map(|p| self.active_toolchain(p, LanguageName::new_static("Python"), cx))
             .collect::<Vec<_>>();
         let remote_client = self.remote_client.clone();
         let shell = match &remote_client {