Handle vertex data in TESS mode

[davepagurek]

Resolves #5631

Changes:

• Passes all vertex data to Tessy when using beginshape(TESS)
• Updates Tessy callbacks to properly interpolate data at intersection points

Screenshots of the change:

let tex; function preload() { tex = loadImage('cat.jpg'); } function setup() { createCanvas(400, 400, WEBGL); textureMode(NORMAL) noLoop(); } function draw() { background(220); scale(3, 3); translate(-50, -50); texture(tex); beginShape(TESS); vertex(20, 20, 0, 0); vertex(80, 20, 1, 0); vertex(80, 40, 1, 0.33); vertex(40, 40, 0.33, 0.33); vertex(40, 60, 0.33, 0.67); vertex(80, 60, 1, 0.67); vertex(80, 80, 1, 1); vertex(20, 80, 0, 1); endShape(CLOSE); }	Before	After

PR Checklist

• npm run lint passes
• [Inline documentation] is included / updated
• [Unit tests] are included / updated