feat: Support parsing tap metadata sql-datatype in SQL targets

[edgarrmondragon]

Feature scope

Targets (data type handling, batching, SQL object generation, tests, etc.)

Description

Follow-on from #1323

[edgarrmondragon]

Copying here my comment from #1872 (comment):

One thing that unfortunately isn't very clear to me is how are targets supposed to consume this information since a target isn't aware of the tap's metadata. It might be better if this metadata lived in the schema, at least that way it would be emitted with SCHEMA messages and could be used by the target.

The official Singer docs only explain the field as Represents the datatype of a database column, and pipelinewise's taps implement but the target don't seem to use it in any way:

https://github.com/search?q=org%3Atransferwise+sql-datatype+language%3APython&type=code&l=Python

Otherwise, who is the consumer of this metadata?