Pretty printing methods for jobs/clusters/warehouses.

[zacdav-db]

Experimenting with adding pretty printing methods for the following:

Warehouses:

> head(db_sql_warehouse_list(), 1)
[[1]]
warehouse 0011aa1a1a1a1aa1
  <warehouse-name>
  Type: Serverless
  Size: 2X-Small [0/1]
  State: STOPPED

Jobs:

> head(db_jobs_list(), 1)
[[1]]
job 1111111111111111
  <job-name>
  Owner: <fname>.<lname>@<acme-corp>.com

Clusters:

> head(db_cluster_list(), 1)
[[1]]
cluster 1111-123412-abcdefg
  <cluster name>
  Runtime: 17.3.6
  Node Type: i3.xlarge [single-node]
  State: RUNNING