bitwardenAttachment filename itemid

bitwardenAttachment returns a document from Bitwarden using the Bitwarden CLI (bw). filename and itemid are passed to bw get attachment $FILENAME --itemid $ITEMID and the output is returned.

The output from bw is cached so calling bitwardenAttachment multiple times with the same filename and itemid will only invoke bw once.

!!! example

```
{{- bitwardenAttachment "$FILENAME" "$ITEMID" -}}
```