Robcop 6.4.0

Configurable issue format in extended print_issues report (#1410)

Robocop 6.0 introduced print_issues format with new output formats (including now default extended).
Old parameter for configuring format of the line was renamed to --issue-format but only affects simple
output format.

As partial solution for it, this release adds issue_format parameter to print_issues report that allows
to change format of the line:

> robocop check -c print_issues.issue_format="{source}

set_variable.robot
    |
 17 | Set Variables For Dev
    | ^^^^^^^^^^^^^^^^^^^^^ DOC01
 18 |     No Operation