refactor after learning more about better/modern react practices

[ASong5]

[ASong5]

this commit included the following refactors:

• refactored cache state to allow for caching failed runs
• refactored execAlgo() to make it less redundant and more readable - this required some minor changes in algorithms.js
• added an enum-like object to represent the different algorithms
  • more scalable and avoids throwing string literals everywhere
• changed state algoRunning to visualizationRunning in order to more accurately reflect what is taking place
• replaced all JSON.stringify() comparisons in favour of comparing the actual coordinates of the nodes - this is more efficient and readable