add re_data_anomalies_filtered as var

[suelai]

What

closes re-data/re-data#403

How

Add a var for re_data_anomalies_filtered that can override the alerts. In this way, you can select from re_data_anomalies what anomalies you would like to show in alerts in the UI, and also notify in slack.

After this change, the user can create a model (view, ephemeral, table, anything works) on top of re_data_anomalies, for example, the view anomaly_filters

 SELECT
        *
    FROM
        {{ ref('re_data_anomalies') }}
    WHERE
        table_name LIKE '%my_test_table%'
        AND column_name = 'age'
        AND metric = 'avg'

Then set up re_data:re_data_anomalies_filtered: anomaly_filtersindbt.project.yml` and that is all.

---

Tried it on my current project by loading

packages:  
  - git: https://github.com/suelai/dbt-re-data.git
    revision: b1c137c6bd807e06002b7bba1699a0a05deff8ff

and then set up re_data:re_data_anomalies_filtered: anomaly_filters in my dbt_project.yml where anomaly_filters is an ephemeral model on top of re_data_anomalies
It worked as expected and re_data_alerts is now filtered on anomaly_filters