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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