[SaaS UserCap FE]: Add "Approve" button to pending members table

Description

In #333064 (closed) we listed the pending members awaiting approval in the Seat usage > Pending members tab.

Now we want to add an "Approve" button to each pending member row.

Pending members table

Issue	Concerns
#333064 (closed)	It only adds the table and list the users with badges
#330027 (closed) (👈 you're here)	It adds the "Approve" button to each row in the table

Feature flag

This feature will be implemented under the saas_user_caps FF.

Designs

⚠ New Design 👇🏽

#321934[pending-alert.png] (comment 735382597)