Added support for structs in shader uniforms

[jnsmalm]

Description of change

With this change we can set structs in shader uniforms the same way we can set it using WebGL directly.

shader.uniforms["material.color"] = [1, 1, 1];
shader.uniforms["lights[1].position"] = [0, 1, 0];

Pre-Merge Checklist

• [ x] Tests and/or benchmarks are included
• Documentation is changed or added
• [x ] Lint process passed (npm run lint)
• [x ] Tests passed (npm run test)

[codecov-io]

Codecov Report

Merging #6298 into dev will decrease coverage by 1.09%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##              dev    #6298     +/-   ##
=========================================
- Coverage   78.33%   77.23%   -1.1%     
=========================================
  Files          57      178    +121     
  Lines        2820     9511   +6691     
=========================================
+ Hits         2209     7346   +5137     
- Misses        611     2165   +1554

Impacted Files	Coverage Δ
packages/core/src/shader/Program.js	93.93% <100%> (ø)
...ages/core/src/shader/utils/generateUniformsSync.js	86.2% <100%> (ø)
packages/canvas/canvas-renderer/src/canvasUtils.js	2.35% <0%> (-37.86%)	⬇️
...nvas/canvas-graphics/src/CanvasGraphicsRenderer.js	27.56% <0%> (-7.96%)	⬇️
packages/text-bitmap/src/BitmapFontLoader.js	75% <0%> (-3.44%)	⬇️
packages/text-bitmap/src/BitmapFontData.js
packages/text-bitmap/src/formats/index.js
packages/text-bitmap/src/formats/XMLFormat.js
packages/text-bitmap/src/BitmapFont.js
packages/text-bitmap/src/formats/TextFormat.js
... and 129 more

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[GoodBoyDigital]

this is really cool!

[jnsmalm]

:) What do you other guys think, could we add this to next pixi version?

[bigtimebuddy]

I have no problem with this feature. There are some conflicts because we just finished the TypeScript convert of core, and @GoodBoyDigital has a PR right now that will also conflict. If you can have a little patience, we can work on getting this in.

[ivanpopelyshev]

Yep, lets merge it after @GoodBoyDigital PR.

[jnsmalm]

Cool, should I try to resolve these conflicts or should I just leave it as is?

[bigtimebuddy]

@jnsmalm wait until #6369 is merged and then if you could resolve conflicts after, that'd be awesome.

[jnsmalm]

I resolved the conflicts, so it should be ready now :)

[bigtimebuddy]

Thank you @jnsmalm 🎉