Added stream_name as a form field. Minor fixes to set default values when...

• Added stream name as a new instrument field
  • There is a new form field to type there the stream name when needed. For now added as an optional field. Backend and database script have been also updated according to it
• Added hardcoded values for Purpose and Team in the form fields and sample data in the database
• Fixed Sample Unit values to use pageview or session

A few minor fixes to set default values when launching instruments and loading data when populating the

• the new contextual attribute performer_active_browsing_session_token has been added to the contextual_attributes table in the database
• Today is the default date when you are registering a new instrument (at least temporary)
• Fixed the way we load securityLegalReview when modifying an instrument (we were using a wrong name for that field)

Bug: T366949
Bug: T366946
Bug: T366947