Follow-ups for PR 3137

[dunxen]

The following feedback is outstanding for #3137 (hovering over each is a quick way to see what the comment is about):

• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)
• Implement accepting dual-funded channels without contributing #3137 (comment)

[TheBlueMatt]

We're gonna walk back our v2 enablement for 0.1, so this needs to happen for 0.2.

[dunxen]

We're gonna walk back our v2 enablement for 0.1, so this needs to happen for 0.2.

I'll have those cfg flags re-added this week still. Just travelling home today.