Modify upgrade init to only store upgrade fields

[damiannolan]

Summary

Update the ChannelUpgradeInit handler to only store the upgrade fields and not the timeout and last packet sequence send.

• Remove timeout in MsgChannelUpgradeInit and setting in Upgrade
• Remove setting of last packet sequence sent in Upgrade

This will require updating proof verification of TRY to only verify the upgrade fields set. The MsgChannelUpgradeTry should now take in UpgradeFields instead of an Upgrade for the CounterpartyProposedUpgrade, the field name can be renamed as well

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