detect/port: find unique port points

detect/port: find unique port points

In order to create the smallest possible port ranges, it is convenient
to first have a list of unique ports. Then, the work becomes simple. See
below:

Given, a port range P1 = [1, 8]; SGH1
and another, P2 = [3, 94]; SGH2

right now, the code will follow a logic of recursively cutting port
ranges until we create the small ranges. But, with the help of unique
port points, we get, unique_port_points = [1, 3, 8, 94]

So, now, in a later stage, we can create the ranges as
[1, 2], [3, 7], [8, 8], [9, 94] and copy the designated SGHs where they
belong. Note that the intervals are closed which means that the range
is inclusive of both the points.

The final result becomes:
1. [1, 2]; SGH1
2. [3, 7]; SGH1 + SGH2
3. [8, 8]; SGH1 + SGH2
4. [9, 94]; SGH2

There would be 3 unique rule groups made for the case above.
Group 1: [1, 2]
Group 2: [3, 7], [8, 8]
Group 3: [9, 94]

Ticket 6792
Bug 6414