Add class DrawHelper:
 - Line2D_AA - Creates an emulated AA line using triangles. See Recast/imguiRenderGL::drawPolygon for implementation. Line vertices and colors
      are appended in the specified buffer. No actual drawing is done.
 - Line2D_Pixel - Creates a simple line using LINE primitive topology. Line vertices and colors are appended in the specified buffer.
 - Quad2D
 - QuadBorder2D_AA
 - QuadBorder2D_Pixel
 - Polygon2D
 - PolygonBorder2D_AA
 - PolygonBorder2D_Pixel
 - LineList2D_AA
 - LineList2D_Pixel
 - RoundedRect2D - Also copy from Recast/imguiRenderGL::drawRoundedRect
 - Also 3D equivalents
  - Line, Quad, QuadBorder, Box, BoxBorder

 - Then I also need draw* equivalents of those methods. draw equivalents will also create the buffer and submit the draw call.
   - draw equivalents accept a time for how long to display the element, if 0 it will only be displayed for one frame
   - all elements should be grouped into a common vertex/index buffer (as much as possible)
   - draw methods should combine methods above to make drawing easier. e.g. a transparent box with AA line borders should be easily drawable