fix join select issue

[drizk1]

• fixes issue when grouping on a join id
• fixes cte construction issue
• fixes select before join order execution issue
• add ~ support for aggregate functions in mutate, similar to TidierData syntax
• additional AWS/Athena Backend improvements

#143
#148
#149

[drizk1]

julia> @chain mtcars begin 
            @group_by(cyl)
            @mutate(kurt = ~kurtosis(mpg))
            @select cyl mpg kurt
            @head()
            @collect 
       end
6×3 DataFrame
 Row │ cyl    mpg      kurt     
     │ Int64  Float64  Float64  
─────┼──────────────────────────
   1 │     6     21.0  -1.82944
   2 │     6     21.0  -1.82944
   3 │     6     21.4  -1.82944
   4 │     6     18.1  -1.82944
   5 │     6     19.2  -1.82944
   6 │     6     17.8  -1.82944