FlxText shadow/outline issues

[Geokureli]

Multiple issues detected with outlines:

• shadowOffset` behaves weirdly: it defaults to (1,1) and it moves both the text and shadow when borderSize != 0
• Shadow gets cut off when shadowOffset is outside the image: Should increase the image size. might be fixed by Fix text clipping when applying a shadow to it #3226
• Outline gets cut off when size too big: should use a bigger image, like above
• Increasing graphic size for border causes issues: for negative shadows or large outlines do we set offset? If we increase the graphic size will that break existing games, where specific?

[Geokureli]

For 1 and 2, I kinda feel like we should deprecate shadowOffset altogether and add a new border style

/**
 * A shadow that allows custom placement.
 * Note: Ignores `borderSize`
 */
SHADOW_CUSTOM(offsetX:Float, offsetY:Float);

For 3 and 4, we need to determine an image size that includes the desired outline, much like @Vortex2Oblivion did in 3226, but for all border styles

[Geokureli]

Proposed Fix - #3236