3.x: Add missing throwIfFatal calls

[akarnokd]

• Add missing Exceptions.throwIfFatal calls in catch (Throwable blocks.
• Add validator that checks for the existence of these throwIfFatal, wrapOrThrow or fail calls.
• Fix AutoCloseableDisposable to use wrapOrThrow like the other Disposable wrapper implementations.

Resolves #6796

[codecov]

Codecov Report

Merging #6801 into 3.x will increase coverage by <.01%.
The diff coverage is 87.87%.

@@             Coverage Diff              @@
##                3.x    #6801      +/-   ##
============================================
+ Coverage     98.24%   98.24%   +<.01%     
- Complexity     6375     6378       +3     
============================================
  Files           711      711              
  Lines         46214    46247      +33     
  Branches       6330     6330              
============================================
+ Hits          45403    45437      +34     
- Misses          289      291       +2     
+ Partials        522      519       -3

Impacted Files	Coverage Δ	Complexity Δ
.../internal/operators/flowable/FlowableDoOnEach.java	93.25% <0%> (-2.15%)	3 <0> (ø)
...ternal/operators/observable/ObservableCollect.java	100% <100%> (ø)	2 <0> (ø)	⬇️
...ternal/schedulers/ScheduledDirectPeriodicTask.java	100% <100%> (ø)	2 <0> (ø)	⬇️
...nternal/operators/flowable/FlowableScalarXMap.java	100% <100%> (ø)	7 <0> (ø)	⬇️
...nal/operators/observable/ObservableScalarXMap.java	97.72% <100%> (+0.02%)	7 <0> (ø)	⬇️
...java3/internal/schedulers/InstantPeriodicTask.java	100% <100%> (ø)	20 <0> (ø)	⬇️
...s/observable/ObservableWindowBoundarySelector.java	96.44% <100%> (+0.01%)	2 <0> (ø)	⬇️
...ators/flowable/FlowableWindowBoundarySelector.java	95.26% <100%> (+0.02%)	2 <0> (ø)	⬇️
...nternal/operators/observable/ObservableReplay.java	96.3% <100%> (ø)	19 <0> (ø)	⬇️
.../operators/observable/ObservableCollectSingle.java	100% <100%> (ø)	3 <0> (ø)	⬇️
... and 39 more

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