style: change style settings for better format standard

[yunchae-kim]

[#62] Refer to GitHub issue...

This update does the followings to implement better coding style guide standard based on Airbnb Style Guide, ESLint, Prettier, and PEP8.

.editorconfig

• Added file to implement necessary format settings across different IDEs including VSCode.

.eslintrc

• Removed Typescript related extensions and plugins as it prompts ESLint unnecessary warnings. Will be implemented again once Typescript is used.
• Import plugin added to lint import-related codes.
• Several rules were included to overrule Prettier with Airbnb rules, which we figured were better coding practices. The followings are included: react/no-multi-comp semi, comma-dangle, no-underscore-dangle, space-before-blocks, keyword-spacing, spaced-comment, quotes, prefer-template, template-curly-spacing, jsx-quotes, camelcase, no-unused-vars.
• Import rules were added to match with Airbnb style guide.
• Rules are subject to change in the future and documentation regarding the changes will be written.

.prettierrc

• Some rules were changed to overrule Prettier with Airbnb rules.

.vscode/settings.json

• Editor indent setting was removed as it is now included in .editorconfig.

package.json

• Removed Typescript related extensions and will be implemented in the future once Typescript is used.
• Airbnb related ESLint plugins were added to enforce Airbnb style guide rules.
• StyleLint was added to organize CSS files. The tool is being tested and may be removed in the future.