Add LL control PDU emulation and improve device.py test coverage

[zxzxwu]

Summary

This PR significantly improves test coverage and Bluetooth Core Specification v6.3 compliance for bumble/device.py and bumble/controller.py by implementing
Link Layer (LL) control PDUs and over-the-air physical emulation procedures instead of relying on direct cross-controller dictionary lookups or HCI mocks.

bumble/device.py test coverage is increased from 67.65% (1,976/2,921 lines) to ~77% (+260 lines covered).

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Key Changes

1. Link Layer Control PDUs (bumble/ll.py)

Added spec-accurate Link Layer Control PDUs and over-the-air Extended Advertising extensions:

• Extended Advertising: Extended AdvExtInd with sid (Set ID from ADI) and periodic_advertising_data payload.
• Connection Parameters & Subrating: Added ConnectionUpdateInd, ConnectionRateInd, and SubrateInd.
• Channel Sounding (CS): Added CsConfigReq, CsConfigRsp, CsSecReq, CsSecRsp, CsReq, CsRsp, and CsInd.

2. Spec-Compliant Controller & Link Layer Emulation (bumble/controller.py)

Implemented full Bluetooth Core Spec v6.3 Message Sequence Chart (MSC) flows in Controller:

• Over-the-Air Periodic Advertising Synchronization:
  • Replaced cross-controller LocalLink.find_advertising_set lookups with realistic over-the-air ll.AdvExtInd PDU matching by (AdvA, SID).
  • Added support for HCI_LE_Periodic_Advertising_Create_Sync_Command (sync_timeout expiration handling),
    HCI_LE_Periodic_Advertising_Create_Sync_Cancel_Command, and HCI_LE_Periodic_Advertising_Terminate_Sync_Command.
  • Automatically emits HCI_LE_Periodic_Advertising_Sync_Established_Event and HCI_LE_Periodic_Advertising_Report_Event when matching AdvExtInd PDUs are
    received over the air.
• Broadcast Isochronous Group (BIG / BIS):
  • Implemented on_hci_le_create_big_command, on_hci_le_terminate_big_command, on_hci_le_big_create_sync_command, and on_hci_le_big_terminate_sync_command.
• Connection Parameter Update & Subrating:
  • Implemented on_hci_le_connection_update_command, on_hci_le_connection_rate_request_command, and on_hci_le_subrate_request_command using
    ConnectionUpdateInd, ConnectionRateInd, and SubrateInd LL Control PDUs to update both initiator and peer connection states.
• Channel Sounding (CS):
  • Implemented on_hci_le_cs_create_config_command, on_hci_le_cs_security_enable_command, on_hci_le_cs_set_procedure_parameters_command, and
    on_hci_le_cs_procedure_enable_command with bidirectional LL PDU exchanges (CsConfigReq/Rsp, CsSecReq/Rsp, CsReq/Rsp/Ind).

3. Bug Fixes (bumble/device.py)

• Fixed PeriodicAdvertisingSync.on_establishment state handling so that host-initiated cancellation responses (status == HCI_OPERATION_CANCELLED_BY_HOST_ERROR) are properly processed as cancellations (State.CANCELLED) rather than being misinterpreted as late establishment events.

4. Comprehensive End-to-End Emulation Tests (tests/device_test.py)

Added 8 end-to-end two-device emulation tests verifying both local and remote peer states:

• test_connection_parameters_and_subrate: Validates connection parameter updates, connection rate requests, and subrate updates across both peer controllers.
• test_periodic_advertising_sync: Validates single Periodic Advertising train synchronization and report reception over the air.
• test_big_and_big_sync: Validates BIG creation and BIG sync establishment over a Periodic Advertising train.
• test_multiple_periodic_advertising_and_big_syncs: Validates concurrent synchronization to multiple Periodic Advertising trains (SID=0 and SID=1) with
  distinct payloads and multiple BIG syncs.
• test_periodic_advertising_and_big_failure_exceptions: Validates failure and exception patterns including duplicate PA sync (ValueError), BIG sync on
  unestablished PA sync (InvalidStateError), PA sync cancellation before establishment (State.CANCELLED), over-the-air sync timeout
  (CONNECTION_FAILED_TO_BE_ESTABLISHED_ERROR), and BIG handle exhaustion (OutOfResourcesError).
• test_channel_sounding: Validates full Channel Sounding config, security enable, procedure parameters, and procedure enable across both initiator and responder
  devices.
• test_find_peer_by_name_and_identity_address: Validates LE extended scanning and peer discovery by name and identity address.
• test_device_configuration_load_from_dict: Validates DeviceConfiguration dictionary parsing.

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Test Plan

• Executed full test suite via pytest (988 passed, 2 skipped).