[JSON] Update JSON field handling

[fivetran-catfritz]

Copied from fivetran/dbt_amplitude #24.

The following fields are currently treated as JSON-like strings. We need to update their handling to support the new JSON datatype.

Table	Column	Usage Type	Affects	Comments	Link
account	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__account.sql
card	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__card.sql
charge	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__charge.sql
credit_note	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__credit_note.sql
customer	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__customer.sql
dispute	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__dispute.sql
invoice	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__invoice.sql
invoice_line_item	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__invoice_line_item.sql
payment_intent	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__payment_intent.sql
payment_method	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__payment_method.sql
payout	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__payout.sql
plan	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__plan.sql
price	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__price.sql
refund	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__refund.sql
subscription	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__subscription.sql
transfer	metadata	extract	core	has to be enabled by a var	https://github.com/fivetran/dbt_stripe_source/blob/main/models/stg_stripe__transfer.sql