window rule column generation order

[joohokim1]

Describe the bug
The preceeding expression goes latter.

To Reproduce
Steps to reproduce the behavior:

1. Import finefood.sample.txt "with colon delimiter."
2. Click the generated I.DS.
3. Click Create dataflow with this dataset.
4. Edit rules.
5. Drop column3 and all after.
6. Select window command.
7. Input 3 expressions - lead(column1, 0), lead(column1, 1), lead(column1, 2)
8. Click Done.
9. The new columns order is the result of lead(column1, 2), lead(column1, 1), lead(column1, 0)

Expected behavior
The order of the expressions the user entered would be better.

Screenshots

Additional context
There is a logic that a new column comes right after the target column. (if any)
But, in this case, all the expressions should be appended in series.

[joohokim1]

1st integrated test passed.