Use extendPluggableElement for context menu items

[garrettjstevens]

Inspired by #2226, this makes it so that plugins that want to add context menu items to displays now do so using the Core-extendPluggableElement extension point. This removes the need for there to be an autorun that watches for new displays and adds "additionalContextMenuItems" to them. Instead, it extends the display state model itself so all instances of the display already have the additional context menu items.

[garrettjstevens]

May be helpful to look at the diff ignoring whitespace.

[codecov]

Codecov Report

Merging #2229 (40bfb3e) into main (5c8734c) will decrease coverage by 0.07%.
The diff coverage is 41.25%.

@@            Coverage Diff             @@
##             main    #2229      +/-   ##
==========================================
- Coverage   62.89%   62.81%   -0.08%     
==========================================
  Files         484      484              
  Lines       22724    22693      -31     
  Branches     5157     5133      -24     
==========================================
- Hits        14292    14255      -37     
- Misses       8162     8168       +6     
  Partials      270      270              

Impacted Files	Coverage Δ
plugins/alignments/src/index.ts	100.00% <ø> (ø)
plugins/dotplot-view/src/index.ts	24.44% <24.56%> (-7.25%)	⬇️
plugins/linear-comparative-view/src/index.tsx	18.71% <77.77%> (-5.36%)	⬇️
...lugins/alignments/src/LinearPileupDisplay/model.ts	63.58% <100.00%> (-0.74%)	⬇️
...ments/src/LinearSNPCoverageDisplay/models/model.ts	66.66% <100.00%> (ø)
...BaseLinearDisplay/components/BaseLinearDisplay.tsx	87.23% <100.00%> (ø)
...aseLinearDisplay/models/BaseLinearDisplayModel.tsx	78.61% <100.00%> (+0.27%)	⬆️
plugins/dotplot-view/src/DotplotView/model.ts	61.30% <0.00%> (-1.20%)	⬇️
packages/core/util/index.ts	79.84% <0.00%> (ø)

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[rbuels]

Looks fine to me as is.

There is opportunity to use extension points more directly for context menu items though, such as each display making a 'MyDisplay-contextMenuItems' extension point and letting other plugins add to that

[cmdcolin]

I think this is a good change as well. It is breaking since it removes the previously recommend addAdditionalContextMenuItems approach but I'd say we can go for it

[cmdcolin]

Fixed up a merge conflict here, and moved the large dotplot onClick callback to a new function ...should be good to go now though