Update UI of tool messages

- Bring tool messages in line with original envisioned UI of: https://screenshot.googleplex.com/9yZCX636LzpMrgc
  - In particular this represents more descriptive names. FWIW we already had this tech we just weren't passing around information correctly (`displayName` vs. `name`)
 - Add gray to our list of color pallete's and removed Background (unused)
 - Re-enabled representing canceled messages
 - Migrated back towards a cleaner tool message design of status symbols & border colors vs. overly verbose text.
 - Removed border from confirmation diffs.
Fixes https://b.corp.google.com/issues/412598909

packages/cli/src/ui/hooks/useGeminiStream.ts

@@ -269,7 +269,7 @@ export const useGeminiStream = (
             // Create the UI display object matching IndividualToolCallDisplay
             const toolCallDisplay: IndividualToolCallDisplay = {
               callId,
-              name,
+              name: cliTool.displayName,
               description,
               status: ToolCallStatus.Pending,
               resultDisplay: undefined,