Add debounce utility snippet

[iluwatar]

Description:

Create a reusable Java utility to debounce method calls. The method should delay execution of a task until a fixed period has passed since the last invocation. This is particularly useful in GUI applications and search fields to prevent spamming actions.

Acceptance Criteria:

• New debounce snippet has been added
• Method signature could be debounce(Runnable task, long delayMillis) or something similar
• Task is executed only if no call was made within delayMillis
• Include a test that proves the code is working (e.g. using ScheduledExecutorService)