feat: new first channel flow

[rolznz]

Closes #313

The checklist item now goes to a new "first channel" page which uses the Alby LSP proxy to request an order. If Alby doesn't pay the invoice, the user will be directed to the channel order page to pay it. Otherwise, they simply wait for the channel to be opened. On the channel success page, the user's remaining funds will automatically be sent to their new channel.

Using a LSP is now the primary flow, with a link added to go to the outgoing channel flow.

TODOs:

• Improve First Channel page design
• Add links to use onchain / fiat from LSPS1 order page
• Test unpaid private channel open (mutinynet)
• Test unpaid public channel open (mutinynet)
• Full test with production network + drained funds
• Full test with free channel (paid by subscription) - cannot be done as part of this PR
• Retest original (advanced) LSPS1 flow - should not be affected
• "Buy or Deposit" is wrong - it goes to increase spending capacity flow
• Move migration of shared alby funds to new flow