fix(auth): debounce getToken() function

[nkomonen-amazon]

Problem:

The Identity team noticed a large spike in token refreshes for specific users. One user would trigger refresh over 50 times within a few seconds.

Ticket: P180886632

Solution:

The telemetry showed that getChatAuthState() was being called many times in a short period. This eventually triggered the token refresh logic many times, if the token was expired.

The solution is to add a debounce to getToken() which calls the refresh logic.

• debounce() only accepts functions without any args, the refresh logic requires args
• getToken() will also load from disk is the token is not expired, so debouncing here saves disk I/O as well.

The current debounce interval is 100 milliseconds, which based on telemetry should be enough to capture the barrage of calls. With some manual testing it does not feel like UX is impacted in any noticeable way.

---

• Treat all work as PUBLIC. Private feature/x branches will not be squash-merged at release time.
• Your code changes must meet the guidelines in CONTRIBUTING.md.
• License: I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

• This pull request modifies code in src/* but no tests were added/updated.
  • Confirm whether tests should be added or ensure the PR description explains why tests are not required.
• This pull request implements a feat or fix, so it must include a changelog entry (unless the fix is for an unreleased feature). Review the changelog guidelines.
  • Note: beta or "experiment" features that have active users should announce fixes in the changelog.
  • If this is not a feature or fix, use an appropriate type from the title guidelines. For example, telemetry-only changes should use the telemetry type.