feature(dynamodb): delete items for specific hashkey and any sortkey

[wtho]

When using the CLI to delete a dynamodb item via hash key, a sort key also has to be specified if several items exist for a single hash key.

partition key	sort key	value
abc123	main	{ "something": 123 }
abc123	sk1	{"somethingElse": "yeah"}
abc123	sk2	{"somethingElse": "oh no"}

Sometimes it is desired to delete all items for a specific hash key (here abc123), which can take a long time when done manually for each item individually.