Make Babel compile Bootstrap imports

[IanDelMar]

Description

This PR explicitly sets the Babel presets option in rollup.config.js.

Motivation and Context

Not explicitly setting the presets option results in imports from node_module (like Bootstrap) not being compiled. Now that we're using Bootstrap src files compilation is necessary.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring (a code change that neither fixes a bug nor adds a feature)
• Styling (changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc))
• Development (changes that affect the build system or external dependencies)
• Documentation (changes that affect existing inline documentation)

Checklist:

• I pulled my branch from develop.
• I am submitting my pull request to develop.
• I have resolved any conflicts merging this pull request would create.
• I have checked that there aren't other open Pull Requests for the same update/change.
• My code follows the code style of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• (Optional) My change requires a change to the documentation.
• (Optional) I have updated the documentation accordingly.
• (Optional) My change requires a change to the translations.
• (Optional) I have updated the translations accordingly.
• composer phpcs has passed locally.
• composer php-lint has passed locally.
• composer phpmd has passed locally.
• composer phpstan has passed locally.
• I have read the CONTRIBUTING document.

Further comments

Alternatively, one could place babel.config.js in the root directory and remove the babel setting in package.json. @bacoords I recommend treating this as a high priority PR.