Add a separate modal to show overage when user is promoted from guest

Add a Vue component that would be shown every time a user that is being promoted from Guest to a higher role.

Design here

This modal should live on the project members page (ex: gitlab-org/gitlab-shell/-/project_members)

Implementation details:

Task	Status	MR
Create modal UI behind FF	workflowcomplete	!105613 (merged)
Connect company name data to modal, similar to this MR	workflowcomplete	!106934 (merged)

• We need to use a confirm_modal so that we can block the role dropdown change before the user selects an option in the overage modal

• There is a similiar modal implemented in the InviteModalBase component but it is too tightly coupled with the invite members modal itself due to desired transition effect. Let's use every possibility to reuse links/styles from it.

• We need to intercept event that is happening in RoleDropdown. Please keep in mind that it is not an EE component, we would need an EE wrapper above it with handleSelect/handleCancel listeners that would pause/continue the flow.

• We are only interested to show the modal if the user is promoted from Guest. There is a more complex logic we want to use in the future described in the #199893 (comment 958470462) but for this issue it's enough

• The component should be only used in RoleDropdown when show_overage_on_role_promotion feature flag is on.