Enhancement: add include_related parameter to GET/list commands

[stumelius]

Problem

Most GET and list commands are missing the include_related query parameter that the dbt Cloud API supports. This parameter allows callers to embed related objects directly in the response, reducing the number of API calls needed.

Affected commands and valid values

Command	Valid include_related values
account list (v3)	—
account get (v2)	—
project list	repository, connection, group_permissions, docs_job, freshness_job
project get	same as list
environment list	project, connection, credentials, repository
environment get	same as list
job list	environment, custom_environment_variables, most_recent_run, most_recent_completed_run
job get	same as list (tracked separately in #119)
run list	trigger, job, audit, debug_logs
connection get	—

Fix

Add include_related: Optional[str] to each of the above commands and pass it as a query param in execute().

Note: run get already has include_related (as List[str], formatted as a JSON array). The format for other endpoints may differ — confirm against spec before implementing.