[CT-2223] [Spark] Add model-level constraints to get_columns_spec_ddl

[MichelleArk]

Core issue: dbt-labs/dbt-core#6754

from dbt-labs/dbt-core#7067:

constraint type	support
not_null	not enforced
primary_key	not enforced
foreign_key	not enforced
unique	not enforced
check	not enforced

Spark only supports check constraints at the table-level. Add check constraints set at the model-level after check constraints from columns are added: https://github.com/dbt-labs/dbt-spark/blob/main/dbt/include/spark/macros/adapters.sql#L200

Testing coverage is tricky here because the alter statements run after the create table statement: https://github.com/dbt-labs/dbt-spark/blob/main/tests/functional/adapter/test_constraints.py#L8

Constraint docs: https://docs.delta.io/latest/delta-constraints.html