3.x: Add missing exports packages, fix param overrides

[akarnokd]

• Add missing exported packages flowables and operators
• Remove assigning to group, version and description as it breaks the naming of the generated jar file and manifest
• I think the dependency on org.reactivestreams should be transitive as users of RxJava have to interact with RS types too.
• Removed ext.javaCompatibility because looks like it always forced it to Java 8 despite the -PjavaCompatibility provided in the GHA

[codecov]

Codecov Report

Merging #7336 (6ce314a) into 3.x (476aa5c) will increase coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                3.x    #7336      +/-   ##
============================================
+ Coverage     99.53%   99.54%   +0.01%     
+ Complexity     6782     6779       -3     
============================================
  Files           751      751              
  Lines         47482    47482              
  Branches       6378     6378              
============================================
+ Hits          47259    47267       +8     
+ Misses          103       98       -5     
+ Partials        120      117       -3     

Impacted Files	Coverage Δ
...l/operators/observable/ObservableFlatMapMaybe.java	94.36% <0.00%> (-4.23%)	⬇️
...x/rxjava3/internal/operators/single/SingleAmb.java	96.61% <0.00%> (-3.39%)	⬇️
...vex/rxjava3/internal/operators/maybe/MaybeAmb.java	96.96% <0.00%> (-3.04%)	⬇️
...ternal/operators/completable/CompletableMerge.java	97.29% <0.00%> (-2.71%)	⬇️
...o/reactivex/rxjava3/processors/AsyncProcessor.java	97.91% <0.00%> (-2.09%)	⬇️
...ternal/operators/observable/ObservableFlatMap.java	97.87% <0.00%> (-0.36%)	⬇️
...ternal/operators/flowable/FlowableWindowTimed.java	97.19% <0.00%> (-0.29%)	⬇️
...a/io/reactivex/rxjava3/subjects/ReplaySubject.java	99.16% <0.00%> (+0.20%)	⬆️
...al/operators/observable/ObservableWindowTimed.java	97.09% <0.00%> (+0.32%)	⬆️
...a3/internal/operators/flowable/FlowableCreate.java	99.35% <0.00%> (+0.32%)	⬆️
... and 6 more

---

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 abeab97...6ce314a. Read the comment docs.