✨ [RUMF-1288] Collect viewport size

[amortemousque]

Motivation

When looking at clickmaps users need to be able to filter events by viewport size.
I also took to chance to clean a bit RUM domain folder by moving context files in a dedicated folder.

Changes

• Move context files in a dedicated folder
• Collocate context types with their modules
• Add displayContext

Testing

• Local
• Staging
• Unit
• End to end

---

I have gone over the contributing documentation.

[codecov-commenter]

Codecov Report

Merging #1584 (be14888) into main (8577823) will increase coverage by 0.09%.
The diff coverage is 86.66%.

@@            Coverage Diff             @@
##             main    #1584      +/-   ##
==========================================
+ Coverage   90.74%   90.84%   +0.09%     
==========================================
  Files         121      123       +2     
  Lines        4540     4554      +14     
  Branches     1018     1021       +3     
==========================================
+ Hits         4120     4137      +17     
+ Misses        420      417       -3     

Impacted Files	Coverage Δ
packages/rum-core/src/boot/rumPublicApi.ts	94.79% <ø> (ø)
packages/rum-core/src/boot/startRum.ts	26.31% <ø> (ø)
packages/rum-core/src/domain/assembly.ts	100.00% <ø> (ø)
...ages/rum-core/src/domain/contexts/ciTestContext.ts	100.00% <ø> (ø)
...rum-core/src/domain/contexts/foregroundContexts.ts	90.76% <ø> (ø)
...es/rum-core/src/domain/contexts/internalContext.ts	100.00% <ø> (ø)
.../rum-core/src/domain/contexts/syntheticsContext.ts	100.00% <ø> (ø)
...ckages/rum-core/src/domain/contexts/urlContexts.ts	100.00% <ø> (ø)
...kages/rum-core/src/domain/contexts/viewContexts.ts	100.00% <ø> (ø)
...ain/rumEventsCollection/action/actionCollection.ts	95.45% <ø> (ø)
... and 8 more

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[amortemousque]

Getting the display context at the assembly stage is the more straightforward way to implement it.
However, for pre-init calls, it means we won't get the display info of the time the event happens, but at the init time. I think it's good enough though

[BenoitZugmeyer]

💬 suggestion: ‏Apparently getting the window dimension might force the browser to recompute the layout (cf list here). Maybe listen for resize event and cache its value?

[amortemousque]

Indeed, good. Do you think we should do the same here

[BenoitZugmeyer]

that's already what we do :) (but also we throttle the listener)

[amortemousque]

Nice!

[abramjstamper]

I've checked the documentation here. What configuration of @datadog/browser-rum is required to enable getting the viewport size sent to DataDog? I was going to implement a crudely made custom metric and send the data myself, but would rather use a natively-available Data Dog feature. Thanks