Rework LAVA callback data handling
Rework LAVA callback data handling

- introduce LavaCallback class to store callback data
- transform data processing into more OOP way
- extract exception raising methods into smaller groups and refactor try
blocks

Signed-off-by: Michal Galka <35351e7ebb7262d28d7902253ba30ca44ccd1bb4@collabora.com>

kernelci/kernelci-backend,kernelci/kernelci-backend