Add IkFast parameter accessors to IkFast class

[jslee02]

---

Before creating a pull request

• Document new methods and classes
• Format new code files using clang-format

Before merging a pull request

• Set version target by selecting a milestone on the right side
• Summarize this change in CHANGELOG.md
• Add unit test(s) for this change

[codecov]

Codecov Report

Merging #1396 into master will decrease coverage by 0.1%.
The diff coverage is 17.28%.

@@            Coverage Diff             @@
##           master    #1396      +/-   ##
==========================================
- Coverage   57.38%   57.28%   -0.11%     
==========================================
  Files         366      366              
  Lines       27405    27483      +78     
==========================================
+ Hits        15726    15743      +17     
- Misses      11679    11740      +61

Impacted Files	Coverage Δ
dart/dynamics/SharedLibraryIkFast.hpp	100% <ø> (ø)	⬆️
dart/dynamics/IkFast.hpp	100% <ø> (ø)	⬆️
dart/dynamics/SharedLibraryIkFast.cpp	52.74% <0%> (+3.33%)	⬆️
dart/common/detail/SharedLibraryManager.cpp	75% <100%> (ø)	⬆️
dart/dynamics/IkFast.cpp	59.11% <16.43%> (-24.1%)	⬇️