RUMM-1001 Handle types with additionalProperties in JsonSchema

[xgouchet]

What does this PR do?

Handle the additionalProperties feature of JsonSchema (described here).

Motivation

Improve the way we handle the customTimings for view events (cf RUMF-783)

[codecov-io]

Codecov Report

Merging #473 (d42f533) into master (5ecdfeb) will decrease coverage by 0.13%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #473      +/-   ##
============================================
- Coverage     90.15%   90.02%   -0.13%     
  Complexity     1359     1359              
============================================
  Files           160      160              
  Lines          4641     4641              
  Branches        518      518              
============================================
- Hits           4184     4178       -6     
- Misses          286      291       +5     
- Partials        171      172       +1     

Impacted Files	Coverage Δ	Complexity Δ
...internal/tracking/JetpackViewAttributesProvider.kt	73.68% <0.00%> (-15.79%)	8.00% <0.00%> (-1.00%)
...nternal/tracking/OreoFragmentLifecycleCallbacks.kt	89.47% <0.00%> (-5.26%)	14.00% <0.00%> (-1.00%)
...oid/rum/tracking/NavigationViewTrackingStrategy.kt	86.27% <0.00%> (-1.96%)	14.00% <0.00%> (-1.00%)
...ernal/instrumentation/gestures/GesturesListener.kt	89.74% <0.00%> (-1.71%)	44.00% <0.00%> (-1.00%)
...tadog/android/log/internal/domain/LogSerializer.kt	90.00% <0.00%> (-1.43%)	28.00% <0.00%> (ø%)
...g/android/rum/internal/domain/scope/RumEventExt.kt	87.64% <0.00%> (-1.12%)	0.00% <0.00%> (ø%)
...l/net/info/BroadcastReceiverNetworkInfoProvider.kt	81.05% <0.00%> (ø)	28.00% <0.00%> (ø%)
...android/rum/internal/ndk/DatadogNdkCrashHandler.kt	82.95% <0.00%> (+0.78%)	25.00% <0.00%> (+1.00%)
...c/main/kotlin/com/datadog/android/DatadogConfig.kt	94.90% <0.00%> (+1.02%)	12.00% <0.00%> (+2.00%)
...oid/src/main/kotlin/com/datadog/android/Datadog.kt	89.41% <0.00%> (+1.18%)	29.00% <0.00%> (+1.00%)

[mariusc83]

LGTM