RUM-1613 Add mapper interface for traversing all children

[jonathanmos]

What does this PR do?

Add an internal interface for mappers that need to traverse all children during tree traversal.

Motivation

This interface is to be used by React Native for traversing RN view groups, as preparation for implementing Session Replay there.

Additional Notes

Anything else we should know when reviewing?

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[codecov-commenter]

Codecov Report

Merging #1684 (0ca6379) into develop (1fc5582) will increase coverage by 0.06%.
Report is 33 commits behind head on develop.
The diff coverage is 92.31%.

@@             Coverage Diff             @@
##           develop    #1684      +/-   ##
===========================================
+ Coverage    83.73%   83.79%   +0.06%     
===========================================
  Files          459      459              
  Lines        15778    15781       +3     
  Branches      2354     2355       +1     
===========================================
+ Hits         13211    13223      +12     
+ Misses        1938     1933       -5     
+ Partials       629      625       -4     

Files	Coverage Δ
...ssionreplay/internal/recorder/TreeViewTraversal.kt	100.00% <100.00%> (ø)
...essionreplay/internal/recorder/SnapshotProducer.kt	87.88% <66.67%> (ø)

... and 16 files with indirect coverage changes

[xgouchet]

Note

I'm confused about the naming of the interface: It says the mapper is Non exhaustive, but it would imply using a TRAVERSE_ALL_CHILDREN strategy. Can we be a bit more explicit about what is being non exhaustive here?

[jonathanmos]

Until now we've referred to mappers that return a node whenever they map to a specific class as being "exhaustive", and so the naming follows from this. How about "TraverseAllChildrenMapper"?