Use show objects in schema on Snowflake

[drewbanin]

Describe the feature

dbt should leverage the show terse objects in schema query to list the tables and views in a database. Crucially, show .... queries do not require a running warehouse, so they will not queue in the virtual warehouse (leading to long perceived startup times).

Caveats:

• Snowflake's docs indicate that only 10k records can be returned from one of these queries. I'd like to talk to someone from Snowflake to get an understanding if this limit is still accurate, or if they have near-term plans to lift this restriction.
• The existing info schema query gets away with a case-insensitive lookup using `ilike, but we'll need to quote and case the schema name exactly for this query to succeed.
• Per the docs, materialized views are returned with type VIEW, which is kind of unpleasant.
• We should post-process the results in Python instead of using result_scan, because selecting from result_scan can queue