Add column relationship validation to single table metadata

[amontanez24]

Problem Description

As a user, I'd like to know if I formatted the column relationships in my metadata incorrectly so that I don't run methods that will take longer only to have them crash.

The SingleTableMetadata object is being upgraded to accept a new field called column_relationships. The format is as follows:

{
  "columns": {
    "user_lat": { "sdtype": "latitude" },
    "user_lon": { "sdtype": "longitude" },
  },
  "column_relationships": [{
    "type": "gps_coordinate",
    "column_names": ["user_lat", "user_lon" ],
  }]
}

Expected behavior

When running metadata.validate() on SingleTableMetadata, we should perform the following checks:

• type must be a supported relationship type (only "address" for now)
• column_names must all be listed in the "columns" section of the metadata
• The column_names cannot already be involved in any other column relationship
• The column_names cannot be a primary key or a foreign key (listed in the relationships)
• The columns' sdtypes must be compatible with the relationship type. Each type will have different rules for this.
  • Eg. address supports sdtypes: postcode, state, city, …
    If any of the above are invalid, we should raise an InvalidMetadataError.

Additional context

• We should put all of this validation into its own function since it will be reused by the add_column_relationship function in Add add_column_relationship method to single table metadata #1699 .
• We should follow the same validation style as below:
  

  SDV/sdv/metadata/single_table.py

  Lines 557 to 572 in 57feae8

  	def validate(self):
  	"""Validate the metadata.
  	Raises:
  	- ``InvalidMetadataError`` if the metadata is invalid.
  	"""
  	errors = []
  	# Validate keys
  	self._append_error(errors, self._validate_key, self.primary_key, 'primary')
  	self._append_error(errors, self._validate_key, self.sequence_key, 'sequence')
  	if self.sequence_index:
  	self._append_error(errors, self._validate_sequence_index, self.sequence_index)
  	self._append_error(errors, self._validate_sequence_index_not_in_sequence_key)
  	self._append_error(errors, self._validate_alternate_keys, self.alternate_keys)