Let additional arguments pass from db_compute.DBIConnection() to dbplyr_save_query()

[rsund]

Tailored backends may want to support additional arguments in compute(). Unfortunately db_compute.DBIConnection is not passing all arguments to dbplyr_save_query() and therefore additional arguments never reach the sql_query_save() -method.

For example, overwrite argument is not supported in dbplyr (#488). Adding it to tailored backend is more complicated than necessary as additional arguments are not passed through the whole chain from compute() to sql_query_save-method (see duckdb/duckdb#5115).

Fix seems to be easy and non harmful. If that is not the case and/or there is a reason for not letting arguments pass through, please close this PR.

[mgirlich]

On the one hand this makes sense on the other you kind of take away the possibility to use the dots for db_compute() methods.
@hadley What do you think?

[hadley]

My main concern is that it's not at all obvious where those dots go, and what they match against. That makes the risk of unintended consequences high and makes it difficult to document the behaviour.

[hadley]

OTOH there's no other place for ... to go here, and adding it seems generally harmless.