[Upgrade] Test upgrades on Rococo: using referenda system

[shannonwells]

Notes

• @shannonwells has some notes from [Governance] Create and document chain upgrade process + requirements checklist #249 and adding more would be good.
• Recording a video would be good.
• If there is not new code already, to get a upgrade, make a change and manually build a new wasm (needed for storage migration at least)

To Do

• Referenda system: chain upgrade
• Referenda system: Storage migration

[shannonwells]

How to create a new proposal:

This should probably go in a markdown but it's short so I'm putting it here for now:

In a nutshell, to make a proposal through the Polkadot UI, you would go to Governance → Democracy and click “Submit preimage”.

Then you can select an extrinsic to be enacted, providing the needed parameters.
IMPORTANT: whatever extrinsic is submitted for proposal must be able to succeed as the Root origin. For example, if the proposal is to transfer a balance, you would need to submit this as a forceTransfer operation.

Once you choose the extrinsic to execute, the preimage and its hash is constructed for you. There is a storage fee for the proposal based in part on the size of the preimage.

After the submit preimage transaction is included in a block, then you must copy the preimage hash and submit it in the proposal. After the referendum passes, the extrinsic will be executed.

If the proposal is for an upgrade, then you can proceed similarly to a scheduled Sudo upgrade in which you upload the file and submit the proposal using the uploaded WASM file. Note you must still submit extrinsic for authorizing the upgrade before the proposal is enacted, as documented in the link for this issue.

Once you’ve submitted a preimage and it is included in a block, you can go to the Block Explorer panel, then copy the preimage hash by expanding the extrinsic under "recent extrinsics" and submit that.

In a dev environment, to get proposals to work, you’ll need to run the parachain with a relay chain; it doesn’t work with instant sealing.