[tinyusb] Add on_mount/on_unmount triggers and is_mounted condition (#19067)

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

tests/components/tinyusb/common.yaml

@@ -6,6 +6,15 @@ tinyusb:
   usb_product_str: ESPHomeTestProduct
   usb_serial_str: ESPHomeTestSerialNumber
   usb_vendor_id: 0x2345
+  on_mount:
+    - logger.log: USB host mounted
+    - if:
+        condition:
+          tinyusb.is_mounted:
+        then:
+          - logger.log: USB host is mounted
+  on_unmount:
+    - logger.log: USB host unmounted
 
 # tinyusb requires at least one USB class companion; usb_cdc_acm satisfies that.
 usb_cdc_acm: