convert FormulaCompiler::SeparatorType to scoped enum

and drop unused COMMA_BASE enumerator

Change-Id: I5f35ba7453d5ca613ebd65d0853c7caaa210f3de
Reviewed-on: https://gerrit.libreoffice.org/34357
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

compilerplugins/clang/unusedenumconstants.py

@@ -145,6 +145,8 @@ for d in definitionSet:
          "basic/source/inc/token.hxx", # SbiToken
          "binaryurp/source/specialfunctionids.hxx", # binaryurp::SpecialFunctionIds
          "connectivity/source/inc/odbc/OTools.hxx", # ODBC3SQLFunctionId
+         "include/formula/grammar.hxx", # FormulaGrammar::Grammar
+         "include/formula/opcode.hxx", # OpCode
         # Windows or OSX only
          "include/canvas/rendering/icolorbuffer.hxx",
          "include/vcl/commandevent.hxx",