events: form page

[MRita443]

Implement the priority version of the event creation form page, according to the mocks below. This page should be adapted to be an event's edition page too.

Development should include:

• Implementing the new event form
• Verifying mobile version
• Adaptations to develop the event edition form
• Linking in event detail and listing pages
• Developing functionality and interaction tests

[MRita443]

In order for this forms to have the event sponsor logos, this backend issue should be addressed first: NIAEFEUP/website-niaefeup-backend#208.

[MRita443]

It was agreed that for the MVP, sponsor images won't be featured yet!