Replace IndexFactory reflection.

[lbergelson]

• IndexFactory used old reflection code that was unnecessarily brittle and may cause problems in java 11. Replaced it by using direct references to Index constructor methods instead of finding them with reflection.

• Breaking changes: Removed public methods IndexType.getIndexCreator() and IndexType.getIndexType(). The first of these was broken and always resulted in an exception and the second is mostly useless and also unlikely to be missed.

• It would be good to look at canCreate and understand what it's purpose is and if it still makes sense. The whole group of IndexConstructors/Indexes/IndexFactory methods seems like there is something fundamentally wrong with the design.

Things to think about before submitting:

• [ ] Make sure your changes compile and new tests pass locally.
• [ ] Add new tests or update existing ones:
  • A bug fix should include a test that previously would have failed and passes now.
  • New features should come with new tests that exercise and validate the new functionality.
• [ ] Extended the README / documentation, if necessary
• [ ] Check your code style.
• [ ] Write a clear commit title and message
  • The commit message should describe what changed and is targeted at htsjdk developers
  • Breaking changes should be mentioned in the commit message.

[lbergelson]

@cmnbroad Some cleanup in this class. It's a similar change to https://github.com/samtools/htsjdk/pull/1421

[codecov-io]

Codecov Report

Merging #1431 into master will increase coverage by <.001%. The diff coverage is 77.778%.

@@               Coverage Diff               @@
##              master     #1431       +/-   ##
===============================================
+ Coverage     68.375%   68.376%   +<.001%     
- Complexity      8486      8488        +2     
===============================================
  Files            583       583               
  Lines          34375     34369        -6     
  Branches        5732      5730        -2     
===============================================
- Hits           23504     23500        -4     
  Misses          8650      8650               
+ Partials        2221      2219        -2

Impacted Files	Coverage Δ	Complexity Δ
...java/htsjdk/tribble/index/TribbleIndexCreator.java	100% <100%> (ø)	4 <0> (ø)	:arrow_down:
.../java/htsjdk/tribble/index/linear/LinearIndex.java	77.907% <60%> (ø)	18 <2> (ø)	:arrow_down:
...c/main/java/htsjdk/tribble/index/IndexFactory.java	76.51% <80.952%> (+1.026%)	28 <1> (+1)	:arrow_up:
src/main/java/htsjdk/tribble/TribbleException.java	51.282% <0%> (-7.692%)	5% <0%> (ø)
...htsjdk/samtools/util/nio/DeleteOnExitPathHook.java	90.476% <0%> (+9.524%)	4% <0%> (+1%)	:arrow_up: