Query Folding Improvements

Based on the community's findings we'd welcome a second look at the following Power Query functions vs the equivalent SQL server functionality for improvements to Query Folding.

These changes would enable faster dataset refreshes where applicable and improve the overall experience of using Power Query against relational data sources.

Name----------------------------------Supports Folding--------SQL
Character.FromNumber------------FALSE---------------------CHAR
Text.PositionOf------------------------FALSE--------------------CHARINDEX
Date.AddDays-------------------------FALSE---------------------DATEADD
Date.AddQuarters--------------------FALSE---------------------DATEADD
Date.AddWeeks-----------------------FALSE---------------------DATEADD
Date.DayOfWeekName-------------FALSE---------------------DATENAME
Date.EndOfMonth--------------------FALSE---------------------EOMONTH
Text.At-----------------------------------FALSE---------------------SUBSTRING
Text.Start-------------------------------FALSE---------------------LEFT
Text.Replace--------------------------FALSE---------------------REPLACE
Text.Repeat----------------------------FALSE---------------------REPLICATE
Text.Reverse--------------------------FALSE---------------------REVERSE
Text.End--------------------------------FALSE---------------------RIGHT
Text.ReplaceRange-----------------FALSE---------------------STUFF
Text.Range----------------------------FALSE---------------------SUBSTRING