FEATURE: Invisibly return `db_table` from `defer_db_cleanup()`

[RasmusSkytte]

Describe the feature
By passing the table out after the call we can use defer_db_cleanup() nicely in a pipe context.

What use will this feature have?
Currently, we have to do something like

table <- ds$get_feature(...)
SCDB::defer_db_cleanup(table)

table |> 
  ...

With the change we can simplify the code:

table <- ds$get_feature(...) |>
  SCDB::defer_db_cleanup(table) |> 
  ...

Who should add the feature?
N/A

Additional context
N/A