Allow to configure test name in selecting Relationships

[Dat Nguyen]

Is your feature request related to a problem? Please describe.
If dbt project was using dbt_constraints, they're using the test named foreign_key.

Describe the solution you'd like
We should support that with the configurable input of the test name. Default test name containing relationship wording.

Describe alternatives you've considered
N/A

Additional context
Sample usage of the dbt-contrainst package:

  - name: DIM_ORDER_LINES
    columns:
      # Single column inline constraints
      - name: OL_PK
        tests:
          - dbt_constraints.primary_key
      - name: OL_UK
        tests:
          - dbt_constraints.unique_key
      - name: OL_CUSTKEY
        tests:
          - dbt_constraints.foreign_key:
              pk_table_name: ref('DIM_CUSTOMERS')
              pk_column_name: C_CUSTKEY