Remove interaction and accessibility namespaces

[bigtimebuddy]

Recently in v5, we removed extract and prepare internal namespaces. I would also like to remove interaction and accessibility namespaces as well. These are not useful for organizing the code since they only contain a small number of classes and it simplifies the code and documentation. Internal namespacing is only really useful for utils (which would pollute the root PIXI object with lots of generic functions) and filters (which we can hang a lot more filters on with pixi-filters). It should also make it easier for users importing types in the future.

Documentation
https://pixijs.download/dev-namespace-deprecation/docs/index.html

[codecov-commenter]

Codecov Report

Merging #6681 into dev will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               dev     #6681   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           15        15           
  Lines          672       671    -1     
=========================================
- Hits           672       671    -1     

Impacted Files	Coverage Δ
bundles/pixi.js/test/index.js	100.00% <ø> (ø)

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[GoodBoyDigital]

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