track fiat value of payments (#1789)

* save fiat_amounts on payment creation

* show fiat amount in frontend

* add lnbits_default_accounting_currency

* extract fiat calculation logic into service

* move all currency conversions to calc_fiat_amounts

move all conversion logic into create_invoice so extensions can benefit aswell

* show user-defined and wallet-defined currency in frontend

* remove sat from fiat units

* make bundle

* improve tests

* debug log

lnbits/static/i18n/en.js

@@ -29,6 +29,9 @@ window.localisation.en = {
     'This whole wallet will be deleted, the funds will be UNRECOVERABLE.',
   rename_wallet: 'Rename wallet',
   update_name: 'Update name',
+  fiat_tracking: 'Fiat tracking',
+  currency: 'Currency',
+  update_currency: 'Update currency',
   press_to_claim: 'Press to claim bitcoin',
   donate: 'Donate',
   view_github: 'View on GitHub',

lnbits/static/js/base.js

@@ -178,7 +178,8 @@ window.LNbits = {
         id: data.id,
         name: data.name,
         adminkey: data.adminkey,
-        inkey: data.inkey
+        inkey: data.inkey,
+        currency: data.currency
       }
       newWallet.msat = data.balance_msat
       newWallet.sat = Math.round(data.balance_msat / 1000)
@@ -203,7 +204,9 @@ window.LNbits = {
         extra: data.extra,
         wallet_id: data.wallet_id,
         webhook: data.webhook,
-        webhook_status: data.webhook_status
+        webhook_status: data.webhook_status,
+        fiat_amount: data.fiat_amount,
+        fiat_currency: data.fiat_currency
       }
 
       obj.date = Quasar.utils.date.formatDate(