Chores: Add husky and lint-staged to run prettier on staged files

[KixPanganiban]

Changes:

• Added husky and lint-staged to devDependencies
• Added prepare npm script to initialize husky
• Added the following lint-staged directives:
  • eslint for ts and js files
  • prettier for all files that prettier recognizes

How to test:

1. Pull this branch and run npm run prepare
2. Stage a change to a src/ file which contains lines that prettier will obviously format, for example:

   console.log("prettier" +
   "will" +
   "lint this")

3. Commit it with git commit -m "test commit"
4. Confirm that husky runs lint-staged (and by extension, eslint and prettier). You should see a printout similar to this:
   

[dragonman225]

Works great! But whenever I do git commit, eslint creates a .eslintcache file because --cache is turned on. I think it would be better to add that file to .gitignore so that people wouldn't commit it accidentally.

[KixPanganiban]

Happy new year @dragonman225! Just pushed a change adding that file to .gitignore.

[dragonman225]

Happy new year @KixPanganiban!
Merged. Thanks for the pull request!