Add UpgradeTimeoutPath to 24-host

[damiannolan]

Summary

The timeout path is a public path set by the upgrade initiator to determine when the TRY step should timeout. It stores the timeoutHeight and timeoutTimestamp by which point the counterparty must have progressed to the TRY step. The TRY step will prove the timeout values set by the initiating chain and ensure the timeout has not passed. Or in the case of a timeout, in which case counterparty proves that the timeout has passed on its chain and restores the channel.

Add UpgradeTimeoutPath to 24-host with associated key func.

• UpgradeTimeoutPath
• UpgradeTimeoutKey

Ref: 24-host/keys.go

function timeoutPath(portIdentifier: Identifier, channelIdentifier: Identifier) Path {
    return "channelUpgrade/ports/{portIdentifier}/channelIdentifier/{channelIdentifier}/upgradeTimeout"
}

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned

[damiannolan]

Review spec for any updates to key paths

[chatton]

The spec has been updated with

function channelUpgradeTimeoutPath(portIdentifier: Identifier, channelIdentifier: Identifier) Path {
    return "channelUpgrades/ports/{portIdentifier}/channels/{channelIdentifier}/upgradeTimeout"
}

[chatton]

closed by #1821