InteractionManager refactoring: extract TreeSearch

[ivanpopelyshev]

I've got many ideas how to make our interaction code more clear and moddable.

This is first PR in a sequence: I removed 180 lines of code from huge 1900 lines file and got rid of 2 params in a function call.

Here's the biggest case when we need to inject different search behaviour: https://github.com/pixijs/pixi-layers/blob/master/src/InteractionManagerMixin.ts

Several changes in interaction were the reason why users stuck with particular versions of pixijs.

I need help with testing that thing, but it should be easy - I didnt add any new features, just copied the code&docs and passed params.

Why is it separate class, and not a mixin? I think that after several PR's we'll be able to give ability to use treeSearch for hittesting independently of interaction, and with many optional params, like hittesting several objects. Also, someone might do something like

element.on('mousedown', function() { hereIsAnotherHitTest() } );

right now that kind of constructions can affect delayedEvents and other things. Having search-related local variables (queue?) not as params of recursive function will be handy.

Lets start with easy stuff!

And decide on the name...

[codecov-io]

Codecov Report

Merging #6089 into dev will increase coverage by 0.02%.
The diff coverage is 96.82%.

@@            Coverage Diff             @@
##              dev    #6089      +/-   ##
==========================================
+ Coverage   70.87%   70.89%   +0.02%     
==========================================
  Files         208      209       +1     
  Lines       10648    10656       +8     
==========================================
+ Hits         7547     7555       +8     
  Misses       3101     3101

Impacted Files	Coverage Δ
packages/interaction/src/InteractionManager.js	93.31% <100%> (-0.15%)	⬇️
packages/interaction/src/TreeSearch.js	95.83% <95.83%> (ø)

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[bigtimebuddy]

I'm trusting the unit-tests on this one! Code reorg looks good though.

[bigtimebuddy]

Thanks @ivanpopelyshev, good one.