Display Invoice line number and add sorting

Purpose:

Display invoice line number in '#' column on Invoice Details pane instead of the sequence number and add UI-sorting lines by invoice line number.

User story statement(s):

As a user,
I want to see invoice line number and sort invoice lines by invoice line number on Invoice details pane.

Scenarios:

1. Scenario:
   • Given invoice with invoice lines
   • When on details pane looking at "#" column
   • Then the invoice line number is displayed
2. Scenario:
   • Given invoice with invoice lines
   • When Invoice lines are displayed on invoice details pane
   • Then they are sorted by invoice line number in ascending order