Update "Регіони" to be a multi-select choice field [Low Priority]

[AnastasiiaLutsykiv]

As a registered user,
I want to be able to select multiple regions my company is working in,
so that this information is reflected in the profile of my company.

Acceptance criteria

1. Allow multi-select for "Регіон(и)" field
   GIVEN I am in the profile editing pages ("Загальна інформація")
   WHEN I open the "Регіон(и)" dropdown
   THEN I can select multiple values from the list (the same behavior as in the Category field)

2. The selected values in "Регіон(и)" field should be displayed in
   Profile review page,
   Company card in lists

3. If there are many regions selected:

• in profile
• in the card within lists

Out of scope

• display "Регіон(и)" in Нові учасники cards
• redesign of the Regions and Category fields in the Edit profile page (how to display when many are selected)

Linked epic: #6