Update notification for invitation for specific role

[SimoneZaza]

Description

As an admin, I want to invite people directly as admin or lead, instead of waiting for them to accept the invitation before I can promote them to be an admin or lead.

Acceptance criteria

• In invitation notification, change the sentence from
  (name) has invited you to join (space name) on Alkemio
  to
  (name) has invited you to become (a member/a lead/an admin) in (space name) on Alkemio

Additional Context

Related server issue: #3911
Figma: https://www.figma.com/design/y7EcC4ImZuFvbckKNdE1Vt/Invitations?node-id=62%3A156&t=XY5VFHaFIoB3OE2F-1

Areas that will be affected

To be added during the refinement