`applyItemActions` (for graph encryption key management)

[JoeCap08055]

Description

As a Provider/consumer of the Gateway API, I want to be able to manage encryption keys for a user (for Private Graph, or any other purpose). This particular endpoint should be specific to the dsnp private graph encryption key

See @claireolmstead's prs for a pattern

Discussion

• Which version(s) of this extrinsic to support--signed, delegated, or both?
  • Signed only
• Does this belong in account or graph service?
  • account service

[p5150j]

per @wilwade

Account service key mngt and signed by user.