Improved support for dbt_date and dbt_metrics

[RobbertDM]

• dbt_date needs to know how to convert a time zone. trino does that {{ column }} at time zone '{{ target_tz }}'
• dbt_metrics uses some dateadd functionality that looks like this in trino: date_add('day', -5, calendar.date_day)

I did not run any tests except that I succeeded in generating some metrics and using some date functions.

To make this work, one should adapt their dbt_project.yml to include

dispatch:
  - macro_namespace: dbt_date
    search_order: ['trino_utils', 'dbt_date']
  - macro_namespace: metrics
    search_order: ['trino_utils', 'metrics']

We should also probably modify this repo's readme

[mdesmet]

We should probably split this in three different PR and try to add the tests from the respective repo's

[RobbertDM]

split into #19 and #20