Testing line tool

[0HyperCube]

Testcases:

• Works when the viewport is zoomed/panned/tilted
• Works when the artboard has an offset (currently broken Line tool on offset artboard #2485)
• Works when the artboard has a transform before it
• shift constrains to 15 degrees from the viewport (test when the viewport is rotated by 5 degrees)
• Ctrl locks the angle when pressed
• Alt drags from centre (test when combined with shift as well)
• After drawing, selected layers only can have their endpoints dragged.

[prathmesh703]

@0HyperCube can you assign this issue to me?