Allow setting of event_time as a top-level property of a model with a field_name attribute

[QMalcolm]

Housekeeping

• I am a maintainer of dbt-core

Short description

In #10624 we're building a new type of incremental model strategy, microbatch. This will be an awesome system wherein we do reads and writes for incremental via partitions. As part of that, we need a column to partition by. We're gonna call the key for defining that column field_name, and it should live under a top level config property event_time. To specify an event time field name in a model's yaml, it would look something like the following

models:
 - name: my_model
   config:
     event_time: 
       field_name: my_time_field # <-- This is the key/value we're talking about
       ...
   columns: 
     - name: my_time_field
       data_type: timestamp

If you were to specify it in the model's .sql, it would look something like the following

{{
    config(
        materialized = 'incremental',
        event_time = {"field_name": "my_time_field"}, # <-- This is the key/value we're talking about
    )
}}
...

Acceptance criteria

The event_time.field_name configuration is setable via .sql and .yml for models, and this propagates to the eventual node in the manifest

Suggested Tests

• Set event_time.field_name in the configuration of a model .sql file and ensure it propagates to the eventual node in the manifest
• Set event_time.field_name in a model .yml file and ensure it propagates to the eventual node in the manifest

Impact to Other Teams

Affects CA: New optional property on model nodes

Will backports be required?

No

Context

No response

[graciegoheen]

We can close out this old issue as a dupe!

[QMalcolm]

Closing as duplicate of #9490