Wrap postgres column identifiers with quotes to handle reserved keywords

[nasmr]

Encountered this error when trying to use the postgres loader with the following SQL query
"SELECT * FROM \"edgeandnode/ethereum_mainnet@0.0.2\".transactions LIMIT 100"

Output:

Failed to load batch: INSERT operation failed: syntax error at or near "to"
LINE 1: ...ck_hash, block_num, timestamp, tx_index, tx_hash, to, nonce,...
                                                             ^

`FATAL: Permanent error loading batch (not retryable). Stopping client to prevent data loss. Error: INSERT operation failed: syntax error at or near "to"
LINE 1: ...ck_hash, block_num, timestamp, tx_index, tx_hash, to, nonce,...
                                                             ^

The operation was failing because the ethereum_mainnet dataset contained column names that were reserved SQL keywords like to, from, ...

This PR addresses this edge case by wrapping column names with " so that reserved keywords will not throw an error and loading operation can take place normally.

Successful output after fix applied: