GetItemDefinitionProperty returns a string property from a given item definition.
Note that some properties (for example, "name") may be localized and will depend
on the current Steam language settings (see ISteamApps::GetCurrentGameLanguage).
Property names are always composed of ASCII letters, numbers, and/or underscores.
Pass a NULL pointer for pchPropertyName to get a comma - separated list of available
property names. If pchValueBuffer is NULL, *punValueBufferSize will contain the
suggested buffer size. Otherwise it will be the number of bytes actually copied
to pchValueBuffer. If the results do not fit in the given buffer, partial
results may be copied.