render,core: Improve EditText's border and background rendering

[kjarosh]

This PR removes the drawing used for rendering the border and the background and renders them using primitives instead.

It provides two methods for drawing the border and the background:

• draw_device_text_box -- when device fonts are used,
• draw_text_box -- when fonts are embedded.

In order to draw the border properly new methods have been added:

• draw_line -- for drawing a single line (always 1px thick),
• draw_line_rect -- for drawing a rectangle using lines (always 1px thick).

These primitives have been implemented for wgpu, WebGL, and canvas.

Before	After

Additional notes:

• draw_line added in this PR may also be used for rendering the selection caret in the future.

Related to https://github.com/ruffle-rs/ruffle/issues/15003, https://github.com/ruffle-rs/ruffle/issues/1881 (the border is not being transformed anymore).