chg: dev: Created a ReadRequestChainFactory to instantiate all RRCs from a single location

[garvit-gupta]

• Use RRCFactory to instantiate all the RRCs from a single location. This will help in having cleaner code and easy extension.

• Move FileDownloadRequestChain to rubix-core module with all the other RRCs

[codecov-io]

Codecov Report

Merging #287 into master will decrease coverage by 0.8%. The diff coverage is 45.71%.

@@            Coverage Diff             @@
##           master     #287      +/-   ##
==========================================
- Coverage   50.67%   49.86%   -0.81%     
==========================================
  Files          60       61       +1     
  Lines        3025     3040      +15     
  Branches      326      326              
==========================================
- Hits         1533     1516      -17     
- Misses       1404     1441      +37     
+ Partials       88       83       -5

Impacted Files	Coverage Δ
.../qubole/rubix/bookkeeper/RemoteFetchProcessor.java	87.03% <ø> (ø)	:arrow_up:
...java/com/qubole/rubix/core/CachingInputStream.java	0% <0%> (ø)	:arrow_up:
...va/com/qubole/rubix/core/NonLocalRequestChain.java	31.74% <0%> (+31.74%)	:arrow_up:
...om/qubole/rubix/core/NonLocalReadRequestChain.java	15% <0%> (+15%)	:arrow_up:
.../com/qubole/rubix/core/RemoteReadRequestChain.java	70.52% <100%> (-0.61%)	:arrow_down:
...n/java/com/qubole/rubix/bookkeeper/BookKeeper.java	70.94% <100%> (ø)	:arrow_up:
.../com/qubole/rubix/core/CachedReadRequestChain.java	81% <100%> (ø)	:arrow_up:
...om/qubole/rubix/core/FileDownloadRequestChain.java	13% <16.66%> (ø)
...va/com/qubole/rubix/bookkeeper/FileDownloader.java	89.55% <66.66%> (-2.39%)	:arrow_down:
...com/qubole/rubix/core/ReadRequestChainFactory.java	88.88% <88.88%> (ø)
... and 5 more

[garvit-gupta]

RRCFactory was to be preliminary step to implement Dummy Mode. However, a new approach of creating a DummyModeCachingInputStream was adopted and the creation of RRCFactory became unnecessary.