Enable Multipartitioning external tables

[atommych]

Given two partitioning columns like:

          partitions:
            - name: coin
              data_type: string
              path_macro: value_only
              vals: [
                 'btc',
                 'eth'
              ]
            - name: transactions
              data_type: string
              path_macro: value_only
              vals: [
                '/transactions/date=2024-09-19',
                '/transactions/date=2024-09-20'
              ]

The current result is an alter table that does not nest the partitions:

alter table dbt_athena_external_tables_example.aws_public_blockchain add if not exists 
partition (coin='btc') location 's3://aws-public-blockchain/v1.0/btc/'
partition (coin='eth') location 's3://aws-public-blockchain/v1.0/eth/'
partition (transactions='/transactions/date=2024-09-19') location 's3://aws-public-blockchain/v1.0//transactions/date=2024-09-19/'
partition (transactions='/transactions/date=2024-09-20') location 's3://aws-public-blockchain/v1.0//transactions/date=2024-09-20/'

This PR enable us to have a mult-partitions like:

alter table dbt_athena_external_tables_example.aws_public_blockchain add if not exists 
partition (coin='btc', transactions='/transactions/date=2024-09-19') location 's3://aws-public-blockchain/v1.0/btc/transactions/date=2024-09-19/'
partition (coin='btc', transactions='/transactions/date=2024-09-20') location 's3://aws-public-blockchain/v1.0/btc/transactions/date=2024-09-20/'
partition (coin='eth', transactions='/transactions/date=2024-09-19') location 's3://aws-public-blockchain/v1.0/eth/transactions/date=2024-09-19/'
partition (coin='eth', transactions='/transactions/date=2024-09-20') location 's3://aws-public-blockchain/v1.0/eth/transactions/date=2024-09-20/'