Refactor Number Input to use Sass modules

[andreancardona]

This issue is for updating the Number Input to Sass Modules in the @carbon/styles package. In this refactor, we will:

• Copy over styles for for the component to packages/styles/scss/components/number-input/_number-input.scss
  • Any additional files will live in the folder packages/styles/scss/components/number-input/
• Create an _index.scss at packages/styles/scss/components/number-input/_index.scss
• Create a test file at packages/styles/scss/components/__tests__/number-input-test.js
• add the storybook stories to @carbon/react

The _index.scss should:

• @forward the mixin and any variables from _number-input.scss
• Include the styles from _number-input.scss by calling the mixin

The <component>-test.js file should test the following:

• The Public API of the number-input/_index.scss file
• Any configuration options that are present for the file

The _number-input.scss will then need to be refactored to use the new import paths and conventions. You can find common recipes here: #8899 (comment)