Testing line tool

[0HyperCube]

Testcases:

• [x] Works when the viewport is zoomed/panned/tilted (#2559)
• [ ] Works when the artboard has an offset, which this PR has currently broken so this also needs a fix
• [x] Works when the artboard has a transform before it (#2572)
• [x] Shift constrains to 15 degrees from the viewport (test when the viewport is rotated by 5 degrees) (#2490)
• [x] Ctrl locks the angle when pressed (#2490)
• [x] Alt drags from centre (test when combined with shift as well) (#2490)
• [ ] After drawing, selected layers only can have their endpoints dragged.

[prathmesh703]

@0HyperCube can you assign this issue to me?

[rahat2134]

@0HyperCube I want to complete this one, Can you assign me this?