[CT-503] Add method to target keys

[jtcohen6]

In #250, we added logic to explicitly render the SQL binding character as ? instead of %s if the method is odbc:

dbt-spark/dbt/include/spark/macros/materializations/seed.sql

Lines 1 to 3 in fbf9abe

	{% macro spark__get_binding_char() %}
	{{ return('?' if target.method == 'odbc' else '%s') }}
	{% endmacro %}

Turns out that didn't work as we hoped, because {{ target.method }} doesn't actually return anything! Why? The method attribute isn't included among its connection keys, exposed to the Jinja context:

dbt-spark/dbt/adapters/spark/connections.py

Lines 157 to 159 in fbf9abe

	def _connection_keys(self):
	return ('host', 'port', 'cluster',
	'endpoint', 'schema', 'organization')

This makes bugs like #334 much trickier to debug than they should be. dbt's debug-level logs (logs/dbt.log) show %s for all SQL binding parameters, and we just have to trust that sqlparams is magically catching and converting those characters right as the query is being sent off via pyodbc:

dbt-spark/dbt/adapters/spark/connections.py

Lines 280 to 287 in fbf9abe

	# pyodbc does not handle a None type binding!
	if bindings is None:
	self._cursor.execute(sql)
	else:
	# pyodbc only supports `qmark` sql params!
	query = sqlparams.SQLParams('format', 'qmark')
	sql, bindings = query.format(sql, bindings)
	self._cursor.execute(sql, *bindings)

[github-actions]

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