Collect visitor role information via analytics

[ralf57]

Overview

This issue depends on https://github.com/Access4all/adg/issues/158 The idea is to ask the ADG visitors in which role they are using/visiting the ADG website. The collected data would help us with the definition of different UX personas.

Example

Question: How are you using the guide? Answers:

• as a developer on a project
• as a bizdev
• as an accessibility enthusiast willing to learn more

@gracischuetz could help crafting the form

Notes:

• answering is totally optional and is done voluntarily by the visitor
• the data is directly submitted to Matomo (via event tracking, no other storage is required)