Create a new sys.functions table that returns a list of all available functions.
- one row per name or one per argument set. I'm inclined to latter so people can use queries to get to data.
- we need to create a delineation between user functions and internal functions and only show user functions. 'CastInt' isn't something the user should be able to see (or run).
- should we add a description annotation that could be included in the sys.functions table?