✨ [RUMF-605] associate event to parent context by start date (behind flag)

[bcaudan]

Motivation

Events were attached to parent view or action when we received them. It caused some issues in the waterfall display where we could see events starting before the start of the view (or the action) which were very confusing.

Changes

Keep an history of parent contexts to retrieve the one (if any) corresponding to the start time of the event.
Clear automatically old context on session renew or after a time out delay.

Testing

automated tests

---

I have gone over the contributing documentation.

[codecov-commenter]

Codecov Report

Merging #445 into master will increase coverage by 0.45%.
The diff coverage is 96.15%.

@@            Coverage Diff             @@
##           master     #445      +/-   ##
==========================================
+ Coverage   86.98%   87.43%   +0.45%     
==========================================
  Files          32       32              
  Lines        1982     2022      +40     
  Branches      403      410       +7     
==========================================
+ Hits         1724     1768      +44     
+ Misses        258      254       -4     

Impacted Files	Coverage Δ
packages/rum/src/rum.entry.ts	71.69% <0.00%> (ø)
packages/rum/src/userActionCollection.ts	98.00% <ø> (ø)
packages/rum/src/parentContexts.ts	98.21% <98.00%> (-1.79%)	⬇️
packages/rum/src/rum.ts	86.77% <100.00%> (+2.47%)	⬆️
packages/core/src/configuration.ts	88.88% <0.00%> (+4.44%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3d8bd26...dc0918d. Read the comment docs.