12700 snowflake cases - add DS (#359)

* add snowflake datasource

Author: asuncepeda

iterate_snowflake/datasources/fixtures/.gitkeep

@@ -0,0 +1,20 @@
+SCHEMA >
+    `date` Date,
+    `symbol` String,
+    `open` Float32,
+    `high` Float32,
+    `low` Float32,
+    `close` Float32,
+    `volume` Float32,
+    `split_coefficient` Float32
+
+ENGINE "MergeTree"
+ENGINE_PARTITION_KEY "toDate(date)"
+ENGINE_SORTING_KEY "date"
+
+IMPORT_SERVICE 'snowflake'
+IMPORT_CONNECTION_NAME 'sf_conn'
+IMPORT_EXTERNAL_DATASOURCE 'tinybird.samples.stock_prices'
+IMPORT_STRATEGY 'replace'
+IMPORT_QUERY 'SELECT date, symbol, open, high, low, close, volume, split_coefficient from tinybird.samples.stock_prices'
+IMPORT_SCHEDULE '@on-demand'