ci/lava: Extract LAVA proxy and LAVAJob abstractions

ci/lava: Extract LAVA proxy and LAVAJob abstractions

Let's make lava_job_submitter.py cleaner with only parsing and retry
mechanism capabilities.

Moved out from the submitter script:

1. proxy functions
  - moved to lava.utils.lava_proxy.py
2. LAVAJob class definition
  - moved to lava.utils.lava_job.py
  - added structural logging capabilities into LAVAJob
  - Implemented properties for job_id, is_finished, and status, with
    corresponding setter methods that update the log dictionary.
  - Added new methods show, get_lava_time, and refresh_log for improved
    log handling and data retrieval.

Signed-off-by: Guilherme Gallo <guilherme.gallo@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22500>