Add action for fetching vulnerability async

What does this MR do and why?

As we are moving away from loading vulnerability information as part of the main query, this MR add action for fetching vulnerability async. TLDR; fetchVulnerabilities action and its related states are added as part of this MR.

EE: true

This is follow-up from Change data source for project level dependencies (!139686 - merged) • Zamir Martins • 16.8

Related issue: #393061 (closed)

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