[BUG] Support creating Tangle job definitions for job with no body-consuming extractors

[Serial-ATA]

Overview

IntoJobDefinition is implemented for functions that take no arguments: https://github.com/tangle-network/blueprint/blob/d52797640f63cb99587f5410449bf5a488c2567e/crates/tangle-extra/src/metadata/job_definition.rs#L83-L97

but in the case that a function takes, for example, a Context, this impl no long applies.