RAT profile onboarding (EXPOSUREAPP-6027) (#2996)

* RAT Profile Onboarding

* Polishing

* Address PR comments

* Update rat_profile_onboarding_fragment.xml

* Update rat_profile_onboarding_fragment.xml

* Address more comments

* Add click listener

* Update content description

* Fix text

* Update Corona-Warn-App/src/main/res/values/legal_strings.xml

Co-authored-by: janetback <68653277+janetback@users.noreply.github.com>

* Update legal text

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>
Co-authored-by: I502720 <axel.herbstreith@sap.com>
Co-authored-by: janetback <68653277+janetback@users.noreply.github.com>
Co-authored-by: chris-cwa <69595386+chris-cwa@users.noreply.github.com>