Investigate if metatransactions will affect activity tracking

[onbjerg]

Metatransactions seem like they will be supported in the next major aragonOS version. We need to check if this will affect how we track activity for apps and our activity feed.

Resources

• [Prototype] AragonApp: signed calls and multi call execution (aka meta-txs support) aragon/aragonOS#442
• Meta Txs: Adding support for meta transactions in aragon apps (Part 1) aragon/aragonOS#526
• Meta Txs: Adding support for meta transactions in aragon apps (Part 2) aragon/aragonOS#527

[onbjerg]

No longer relevant since we're moving to The Graph (#200).