[18.0][ADD] fleet_telemetry: new module

[douglascstd]

Description

New module fleet_telemetry: a generic, provider-agnostic storage for vehicle
telemetry (GPS positions and tracker data) in the Fleet app.

The goal is to give provider integration modules (Traccar, etc.) a common data
model to push positions into Odoo, instead of each integration defining its own.

Features

• Telemetry Devices (fleet.telemetry.device): trackers identified by
  provider + external reference, linked to a fleet.vehicle, with chatter and
  tracking. Unique per company/provider/reference.
• Telemetry (fleet.telemetry): positions with GPS date, server date,
  latitude, longitude, speed, course, altitude, address and a JSON
  attributes field for any provider-specific data. Unique per
  company/provider/external position reference.
• Stored computed route_day, used for filtering and grouping routes by day.
• _merge_duplicate_telemetry() helper to merge duplicated positions received
  for the same device, GPS date and coordinates (keeps the oldest record, fills
  empty values, merges attributes, keeps the latest server date).
• Menus under Fleet > Configuration > Telemetry; telemetry records are
  read-only in the UI (meant to be created by integrations).
• Access: fleet users can read telemetry and manage devices (no delete);
  fleet managers have full access.

No map rendering dependency on purpose. Maps can be provided by a separate
module.

Tests

Unit tests cover devices (defaults, uniqueness), computed dates, position
uniqueness, attribute merging, duplicate merging (including skipped incomplete
groups) and access rights.

How to test

1. Install fleet_telemetry.
2. Go to Fleet > Configuration > Telemetry > Devices and create a device
   linked to a vehicle.
3. Create telemetry records for that device (e.g. from a shell or an
   integration module) and check them in Fleet > Configuration > Telemetry >
   Telemetry, filtering/grouping by vehicle, device or route day.

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Assisted-by: Claude Opus 5.5 (unit tests and readme fragments)