Add possibility to transfer qt widgets into tcl for the testing purposes

[KochynVolodymyr]

We want to have access to qt widgets from tcl scripts. For example:

% set widget [expr getWidget "console"]
% ...

@alain-rs please describe more requirements for this feature.

[KochynVolodymyr]

This is basically done since no any other requirement.

[alain-rs]

Examples:

set widget [getWidget "console"]
send_action $widget "text_entry" "Hello!"
send_action $widget "text_clear"

set widget [getWidget "editor"]
send_action $widget "open_file" "test.v"
set widget [getWidget "editor" "test.v"]
send_action $widget "highlight" "test.v" 10 << Line