change format of blobbers keys

At the moment, the blobber keys has the following format:

https://github.com/0chain/blobber/blob/staging/docker.local/keys_config/b0bnode1_keys.txt#L1C1-L2

where the first line is public key
and the second line is private key

and we internally convert public to wallet ID.

Due to this keys format, it has become a little tedious to faucet tokens on the blobber wallet. Because blobber will have to go through the steps described here:
https://0chain.slack.com/archives/C03788G8N2D/p1683202995153189?thread_ts=1683111428.140489&cid=C03788G8N2D

Instead of going through this, we could change the keys format of the blobbers. We could change the keys format to wallet.json format.

The issue references the keys file at docker.local/keys_config/b0bnode1_keys.txt. Start by examining how keys are currently read and converted to wallet IDs in the codebase. Look for the wallet.json format used elsewhere in the project to understand the new structure. Test changes by running blobber with the updated keys format to ensure compatibility.

Written by the indexing model from the issue text.