fix(tree-item): move focus outline to item label area (#7581)

**Related Issue:** #6481 

## Summary

This updates `tree-item`'s focus outline to be on the content's area
excluding slotted `tree`/`tree-item` children.

![tree-alt-focus](https://user-images.githubusercontent.com/197440/221788706-00d254bc-f3da-4526-838b-7da83e554e91.gif)

### before

<img width="276" alt="Screenshot 2023-02-27 at 11 54 45 PM"
src="https://user-images.githubusercontent.com/197440/221790180-830cf977-515f-4b88-8684-c7aca0232565.png">

### after

<img width="282" alt="Screenshot 2023-02-27 at 11 59 26 PM"
src="https://user-images.githubusercontent.com/197440/221790154-92e4340d-8a98-4f33-826e-58ed43724a60.png">

packages/calcite-components/src/components/tree-item/tree-item.scss

@@ -6,7 +6,7 @@
 }
 
 .node-actions-container {
-  @apply flex justify-between;
+  @apply flex;
 }
 
 @include calciteHydratedHidden();
@@ -104,15 +104,23 @@
 
 // focus styles
 :host {
-  @apply focus-base;
+  @apply outline-none;
+
+  .node-container {
+    @apply focus-base;
+  }
   &:focus,
   &:active {
-    @apply focus-inset outline-none;
+    .node-container {
+      @apply focus-inset;
+    }
   }
 }
 
 :host(:focus:not([disabled])) {
-  @apply focus-inset outline-none;
+  .node-container {
+    @apply focus-inset outline-none;
+  }
 }
 
 .actions-end {
@@ -146,7 +154,7 @@
 }
 
 .node-container {
-  @apply relative flex items-center min-w-0;
+  @apply relative flex grow items-center min-w-0;
 
   .checkmark,
   .bullet-point {