Enhancement/nested telemetry protos

[oscgonfer]

Rebased onto #7198 (and #7245) for demo purposes. Still draft as it may make breaking changes in other clients if accepted.

This is a proposal to make Telemetry with nested protos (now only in AQ telemetry, but can be expanded to other telemetry modules) to add information regarding sensors in the payload (i.e. who is producing the data).

=== Meshtastic Packet Info ===
🔑 Device ID: 3665040172
📟 Device Name: Oscar Test
🗂️ Packet ID: 509853187
⏰ Timestamp: 2026-01-30T14:31:14Z
📡 Port Number: 67
📦 Full protobuf payload:
{ 'time': 1769783474,
  'air_quality_metrics': { 'sen5xdata': { 'pm10_standard': 1,
                                          'pm25_standard': 2,
                                          'pm40_standard': 2,
                                          'pm100_standard': 2,
                                          'particles_05um': 1200,
                                          'particles_10um': 200,
                                          'particles_25um': 0,
                                          'particles_40um': 0,
                                          'particles_100um': 0,
                                          'pm_temperature': 17.755,
                                          'pm_humidity': 68.51,
                                          'pm_voc_idx': 103.0,
                                          'pm_nox_idx': 1.0,
                                          'particles_tps': 0.581},
                           'scd4xdata': { 'co2': 1354,
                                          'co2_temperature': 15.33608,
                                          'co2_humidity': 81.16884}}}

Related to #9474 and building on protobufs proposal in meshtastic/protobufs#852.

An additional improvement would be to add other values (serial number, or sensor_id/sensor_name).