Chore: payment sent notification improvements

[rolznz]

• refactor to better support multiple notification types
• remove unnecessary properties in payment_received and payment_sent events
• duration is wrong, I need to remove it or rename it (since it's the duration since the invoice was created) - removed the duration property for now
• When originally implementing notifications which was that "notifications" was being returned in the methods parameter of the get_info call and we didn't even include what notification types are supported there (which would be empty if you don't allow the notifications permission).

get_info now looks like this:

{
  alias: 'NWC',
  color: '#897FFF',
  pubkey: '0219b1a2bf969944e941f72595db5a5dd55531db00972d41bf8099e499dcaea894',
  network: 'signet',
  block_height: 1190784,
  block_hash: '00000043a9e987f7bff8cfb4b5cb3131ddc291c1e8131f889e952f847c4eda17',
  methods: [
    'get_balance',
    'get_info',
    'list_transactions',
    'lookup_invoice',
    'make_invoice',
    'pay_invoice',
    'sign_message',
    'pay_keysend',
    'multi_pay_invoice',
    'multi_pay_keysend'
  ],
  notifications: [ 'payment_received', 'payment_sent' ]
}

I think we should prioritize this issue: getAlby/hub#139