Bug 765920 - Running balance not accurate when sorted different ways

- Renamed option to "Account Balance" to avoid confusion with running
  total.
- Added helper function to ensure running balance and balance forward
  are only shown when transaction are grouped by account and sorted as
  in register. In that case column heading remains "Running Balance"
  and balance forward is shown. Otherwwise column heading is renamed
  "Account Balance" and balance forward is not shown.
- Also added missing code for Common Currency conversion.

libgnucash/engine/gnc-optiondb.cpp

@@ -115,6 +115,8 @@ const OptionAliases Aliases::c_option_aliases
     // ... replaced to …, Dec 2022
     {"Filter By...", {nullptr, "Filter By…"}},
     {"Specify date to filter by...", {nullptr, "Specify date to filter by…"}},
+    // trep-engine:
+    {"Running Balance", {nullptr, "Account Balance"}},
 };
 
 static bool