UX Improvement for Region Selection

[typecastcloud]

Description

There was a change required with tagus clearing house release, which made region field mandatory and limit allowed inputs (see: bug #356 & ux unfriendly fix #357). This solution is not very UX friendly but reduce the amount of invalid inputs.

As an on-boarding customer,
I want to have an easy time selecting the region code depending on my selected country,
so that I won't input a wrong value and have my on-boarding delayed.

Acceptance Criteria

• only region code following the standard can be selected
• only region code for the selected country can be selected

Additional Information

Dependency to eclipse-tractusx/portal-backend