Move fis widgets SQL into scalar functions

Add fis_wdg_* table functions for dashboard widgets and wire them into
FuchsDatabase.sqlproj; update the invoice list procs accordingly.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Fuchs_Database/dbo/Functions/fis_wdg_bankingupload.sql

@@ -0,0 +1,16 @@
+-- =============================================
+-- Description:	Dashboard widget 'wdg_bankingupload' (Bank-Buchungen).
+--              Called from [dbo].[fis_widgets].[sql] as: SELECT * FROM [dbo].[fis_wdg_bankingupload]()
+-- =============================================
+CREATE FUNCTION [dbo].[fis_wdg_bankingupload]()
+RETURNS TABLE
+AS
+RETURN
+(
+    SELECT TOP (1) [label] = N'Letzte Übertragung der Bankdaten am ' + FORMAT(CAST([value] as date), 'dd.MM.', 'de')
+         , [value] = FORMAT(DATEDIFF(DAY, CAST([value] as date), CAST(GETDATE() as date)), '0', 'de') + ' d'
+         , [status] = IIF(DATEDIFF(DAY, CAST([value] as date), CAST(GETDATE() as date)) > 6, 'neg', 'pos')
+      FROM [dbo].[fds__admin_settings]
+     WHERE [type] = 'log' AND [key] = 'bankingtransaction_merge'
+     ORDER BY TRY_CAST([value] as date) DESC
+);