Add support for LEAD() / LAG() with Row[N] arguments

[lukaseder]

As can be seen in this blog post, PostgreSQL allows for ROW types to be passed to LEAD() and LAG() window functions:
http://blog.jooq.org/2014/04/15/how-to-do-this-with-sql-of-course/

Example:

with data
as (
  select 
    row(sektor, row, scene1, scene2) block
  from d
)
select 
  case 
    when lag (block) over(o) is distinct from block 
     and lead(block) over(o) is distinct from block 

It's probably not possible to emulate this in other databases, if it isn't natively supported.

[lukaseder]

This depends on #3889

[lukaseder]

See also: #11998