insert-files accept multiple --pk

[simonw]

Looking at https://sqlite-utils.datasette.io/en/latest/cli-reference.html there are other commands that should accept multiple primary keys as well:

• insert
• upsert
• insert-files

The transform command accepts multiple --pk already.

Originally posted by @simonw in #620 (comment)

[simonw]

No actually insert and upsert already support that:

sqlite-utils/sqlite_utils/cli.py

Lines 869 to 874 in 23be5be

	click.option(
	"--pk",
	help="Columns to use as the primary key, e.g. id",
	multiple=True,
	required=require_pk,
	),