Samples: Signaling reconnect and refresh/cache turn credentials

[sirknightj]

Issue #, if available:

• Add ping  #83, call get ice servers when offer is received to avoid stale ice server… #86, Time-to-first-frame metrics benchmarking and timeline chart #286

Description of changes:

Background

• Currently, the sample application only fetches TURN servers when the button is clicked. TURN server credentials (used to initiate a TURN server connection) expire after 5 minutes (300 seconds).
• Therefore, if you try to re-initiate a connection (e.g. JoinStorageSession again after the 1 hour limit), the connection will fail if TURN is required on the client side.
• Signaling also has a 10-minute idle timeout. If there is no signaling channel activity for 10 minutes, you get disconnected.

Summary

This PR introduces a more robust mechanism for managing ICE server credentials and optionally supports automatic signaling reconnection in master mode. It also improves logging and enhances maintainability by cleaning up redundant code and clarifying logic flows.

Changes

• Added logic to cache the ICE servers and refresh them only when needed, specifically upon receiving an SDP offer.
  • Improves scalability by avoiding unnecessary network usage ensuring efficient use of both browser and backend resources.
  • TURN credentials are cached in-memory (for the current run), and they are not written to localStorage or cookies.
• Added new checkbox (signaling-reconnect) to the UI for enabling signaling reconnection after idle timeout.
  • When enabled (and ingestion mode is not active), the master client will automatically attempt to reopen the signaling channel upon disconnection. (Ideally, we'd use ping frames, but browsers do not have support for it)

Minor Changes

• Ran linter on the rename-output-file.js
• Address comment regarding the log line in rename-output-file.js from Migrate the sample page to v3 #426
• Minor HTML spacing tweak to improve layout under the Advanced settings.

Testing

• Check JoinStorageSession automatically reconnects with the TURN after 1 hour (and GetIceServerConfig is called again).
• Confirmed signaling reconnect triggers on idle disconnect when checkbox is enabled.
• Check master with the signaling reconnect feature can still have viewers joining via TURN more than 5 minutes after the button is pressed.
• Regression tested existing master/viewer flows across default and advanced settings.

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