Create Filters class to store filter functions

Enhanced the generated code to now store the filter functions within an
array contained in a struct similar to other configured parameters.
This allows the generated property watches to use an index within that
array to access a pointer to a Filters class containing a given set of
filter functions. The set of filter functions would then be applied
against all the properties being watched.

Tested:
    Generated code provides structure needed to access filter functions
    Filter functions filter property values that fail the filter(s)

Change-Id: I8f1f882704de521f2ab393530ad7ef096314975d
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/src/test/propertywatchtest.cpp b/src/test/propertywatchtest.cpp
index 5a0c121..1c56658 100644
--- a/src/test/propertywatchtest.cpp
+++ b/src/test/propertywatchtest.cpp
@@ -123,7 +123,7 @@
     MockDBusInterface::instance(dbus);
 
     const std::vector<std::string> expectedMapperInterfaces;
-    PropertyWatchOfType<T, MockDBusInterface> watch({}, watchIndex);
+    PropertyWatchOfType<T, MockDBusInterface> watch(watchIndex);
 
     auto ndx = static_cast<size_t>(0);
     for (const auto& o : convert(watchIndex))