VRF oracle on bridge v2

[DNK90]

Implement Random seed request task handler on bridge-v2. There are 2 main parts: event trigger function and task handling

1/ Event trigger

• Bridge listens to event RandomSeedRequested and trigger function RandomSeedRequestedCallback
• The function then check if the request is finalized or not. If not, it creates a pending "request random" task and store to database and wait to be handled by the task handler

2/ Task handler

• Pending Random Request Tasks are collected periodically from the database. The flow of processing pending task is explained as the following image

• The processing task then is checked if the transaction is success or not. If it failed, increase try count by 1 and update the task to PENDING and return to handling PENDING process

• Task will be marked as failed if any error happened during handling PENDING task. The task try count is increased by 1. If the try count reaches 10 (max try), the task is updated to FAILED