feat(form): add steps component

[miguelgrc]

Closes #80

Added steps component that allows creating wizard-style forms (or simply modular step sections inside of standard forms) with several customization options:

• Vertical or horizontal
• Hide or show previous and next buttons
• Hide step numbers and show a progress bar instead
• Hide step numbers and show dots instead
• Mark previous steps as completed or not

Notes:

• Anchor links work seamlessly and will direct to the desired field in the appropriate step
• Steps with errors will be displayed in red (or the progress bar will take that color if any of them has errors)