chore: migrate blockchain-scraper to nestjs

[FidelVe]

The following PR is for migrating the blockchain-scraper to nestjs to improve current issues with logging, difficulty to add tasks, bloated code logic etc

An initial commit has been created with a a basic framework created as a proof of concept, the changes made in this initial commit are the following:

• old code logic moved to a folder named db-manager-old
• new nestjs logic added to folder called db-manager
• rabbitmq is used as a message broker to handle task execution
• a logic for "recurring tasks" was created to showcase how our current once-a-day task can be executed, the sample code currently execute dummy tasks every 10 seconds but in this logic block we can add the feature to check for the chain period in the ICON blockchain or simply run the recurring tasks once a day based on time
• a logic for "triggered task" was also added. the app exposes one sample endpoint (/subscribe-newsletter) to showcase how we can trigger task that need immediate execution, when the endpoint is called a message is queue in rabbitmq and the task is then consumed and triggered immediately
• Logging was added with winston package and typescript was used

DO NOT merge yet this is a proof of concept