Query does not work with "hierarchical" sets

[olofhagsand]

Given a "hierarchical" cligen set command structure as follows:

  a @{
    b;
    c; @{
      d;
      e;
    }
  }

It is possible to issue command: a c b and a c d b, but query and completion does not work properly.
For example, the following lacks the "b" option:

> a c ?
  <cr>
  d                    
  e    

expected behavior:

> a c ?
  <cr>
  b        <-------------
  d                    
  e    

[olofhagsand]

The cligen match code in match_pattern_sets() uses a result structure made for matches in a single parse-tree level. This works for a single match and for multiple matches on the same level, but does not work in the case shown here where there is a match in two levels: b in one level and d, e in another level.
In order to solve this, the code for matching multiple commands need to be enhanced. Specifically, the match_result structure needs to handle multiple levels.