Add REPL dropdown menu to toolbar (#14493)

TODO: 


- [x] Actions run from menu not firing
- [x] Menu differentiates idle and busy for running kernel

Menu States:
- [x] No session && no support known

No session && no kernel installed for languages of known support
- (TODO after) Intro to REPL
- [x] Link to docs

No session but can start one
- [x] Start REPL
- (TODO after) More info -> Docs?

Yes Session

- [x] Info: Kernel name, language
  example: chatlab-3.7-adsf87fsa (Python)
  example: condapy-3.7 (Python)
- [x] Change Kernel -> https://zed.dev/docs/repl#change-kernel
- ---
- [x] Run
- [x] Interrupt
- [x] Clear Outputs
- ---
- [x] Shutdown


(Release notes left empty as the change will be documented in the REPL
release!)

Reserved for a follow on PR:

```
- [ ] Status should update when the menu is open (missing `cx.notify`?)
- [ ] Shutdown all kernels action
- [ ] Restart action
- [ ] [Default kernel changed - restart (this kernel) to apply] // todo!(kyle): need some kind of state thing that says if this has happened
```


Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
Co-authored-by: Kyle Kelley <rgbkrk@gmail.com>
Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>

crates/repl/src/kernels.rs

@@ -81,6 +81,52 @@ pub enum Kernel {
     Shutdown,
 }
 
+#[derive(Debug, Clone)]
+pub enum KernelStatus {
+    Idle,
+    Busy,
+    Starting,
+    Error,
+    ShuttingDown,
+    Shutdown,
+}
+impl KernelStatus {
+    pub fn is_connected(&self) -> bool {
+        match self {
+            KernelStatus::Idle | KernelStatus::Busy => true,
+            _ => false,
+        }
+    }
+}
+
+impl ToString for KernelStatus {
+    fn to_string(&self) -> String {
+        match self {
+            KernelStatus::Idle => "Idle".to_string(),
+            KernelStatus::Busy => "Busy".to_string(),
+            KernelStatus::Starting => "Starting".to_string(),
+            KernelStatus::Error => "Error".to_string(),
+            KernelStatus::ShuttingDown => "Shutting Down".to_string(),
+            KernelStatus::Shutdown => "Shutdown".to_string(),
+        }
+    }
+}
+
+impl From<&Kernel> for KernelStatus {
+    fn from(kernel: &Kernel) -> Self {
+        match kernel {
+            Kernel::RunningKernel(kernel) => match kernel.execution_state {
+                ExecutionState::Idle => KernelStatus::Idle,
+                ExecutionState::Busy => KernelStatus::Busy,
+            },
+            Kernel::StartingKernel(_) => KernelStatus::Starting,
+            Kernel::ErroredLaunch(_) => KernelStatus::Error,
+            Kernel::ShuttingDown => KernelStatus::ShuttingDown,
+            Kernel::Shutdown => KernelStatus::Shutdown,
+        }
+    }
+}
+
 impl Kernel {
     pub fn dot(&self) -> Indicator {
         match self {
@@ -95,6 +141,10 @@ impl Kernel {
         }
     }
 
+    pub fn status(&self) -> KernelStatus {
+        self.into()
+    }
+
     pub fn set_execution_state(&mut self, status: &ExecutionState) {
         match self {
             Kernel::RunningKernel(running_kernel) => {