Description of Change

This pull request introduces a new example for connecting to multiple BLE servers simultaneously and refactors how BLE characteristic descriptors are managed in the NimBLE client implementation. The main improvements include lazy-loading of descriptors to avoid deadlocks, on-demand retrieval for notifications, and a new example demonstrating multi-server client logic.

New Example: Multi-Server BLE Client

• AddedClient_multiconnect.ino example, which demonstrates how to scan for, connect to, and interact with up to three BLE servers at once, including handling notifications and reconnections.
• Added a correspondingci.yml configuration for the new example, specifying build requirements for BLE support.

Descriptor Management Refactor (NimBLE Client):

• ChangedBLERemoteCharacteristic to lazily retrieve descriptors only when needed (e.g., for notifications or explicit requests), instead of during construction. This avoids potential deadlocks with NimBLE and improves reliability.[1][2]
• UpdatedgetDescriptors(),getDescriptor(), andsetNotify() to automatically retrieve descriptors on-demand if they have not been loaded yet. This ensures correct behavior for notification registration and descriptor access.[1][2][3]
• Fixed the descriptor discovery range inretrieveDescriptors() to use the remote service's end handle, ensuring all relevant descriptors are found.

Test Scenarios

Tested Locally

Related links

Closes#11796
Closes#11811