runtime(vb): update vb indent plugin as vim9script

Include an updated vb indent script using vim9script.
Also update the runtime indent test files

Signed-off-by: Michael Soyka <mssr953@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/indent/testdir/vb.in b/runtime/indent/testdir/vb.in
index 1653ae6..cb964f7 100644
--- a/runtime/indent/testdir/vb.in
+++ b/runtime/indent/testdir/vb.in
@@ -1,6 +1,16 @@
 ' vim: filetype=vb shiftwidth=4 expandtab
 '
 ' START_INDENT
+#Const Debug = False
+
+#If Win64 Then
+' Win64=true, Win32=true, Win16=false
+#ElseIf Win32 Then
+' Win32=true, Win16=false
+#Else
+' Win16=true
+#End If
+
 Public Type GEmployeeRecord     ' Create user-defined type. 
 ID As Integer               ' Define elements of data type. 
 Name As String * 20 
@@ -95,6 +105,9 @@
 Dim rng As Range
 
 Set rng = Range(cellAddr)
+
+' Line continuation is implemented as a two-character sequence-
+' whitespace followed by underscore.
 With rng
 .Cells(1,1).Value = _
 "Line 1 of multiline string; " & _
@@ -102,14 +115,25 @@
 "Line 3 of multiline string"
 End With
 
-' The following lines have whitespace after the underscore character
-' and therefore do not form a valid multiline statement.  The indent
-' script correctly treats them as four single line statements contrary
-' to the author's obvious indent.
-rng..Cells(1,1).Value = _ 
+' This code block omits the leading whitespace character and so 
+' the trailing underscore will not be treated as line continuation.
+With rng
+.Cells(1,1).Value =_
+"Line 1 of multiline string; " &_
+"Line 2 of multiline string; " &_
+"Line 3 of multiline string"
+End With
+
+' The following lines have whitespace after the underscore character.
+' This is contrary to Microsoft documentation but it is reported that
+' some Microsoft editors allow it and will still treat the statement
+' as line-continued.  
+With rng
+rng.Cells(1,1).Value = _ 
 "Line 1 of multiline string; " & _ 
 "Line 2 of multiline string; " & _ 
 "Line 3 of multiline string"
+End With
 
 End Sub
 
@@ -121,6 +145,18 @@
 
 End Sub
 
+Public Static Function TestStatic(addend As Integer)
+Dim Integer accumulator
+accumulator = accumulator + addend
+TestStatic = accumulator
+End Function
+
+Friend Function TestFriend(addend As Integer)
+Static Integer accumulator
+accumulator = accumulator + addend
+TestFriend = accumulator
+End Function
+
 Sub TestTypeKeyword()
 Type EmployeeRecord         ' Create user-defined type. 
 ID As Integer           ' Define elements of data type. 
@@ -131,4 +167,10 @@
 End Type 
 Dim varType As EmployeeRecord
 End Sub
+
+Sub TestDateLiteralAfterLineContinuation
+Dim birthday as Date
+birthday = _
+#January 1, 1901#
+End Sub
 ' END_INDENT