Add a new datasource for dbtcloud_jobs to retrieve multiple jobs

[b-per]

• add new datasource + docs + tests
• fix typo in diagram
• refactor helper a bit

[chasewalden]

Looks good to me.

As a side-note, this does make me think we should eventually go through an clean up uses of int in favor of a fixed-width type (either int32 or int64). Not a big deal for right now, but will help with unnecessary conversions back-and-forth and would prevent hard-to-debug issues between 32 & 64 bit machines in the future