Approves a pending member using an approval token.
The approveByToken() function returns a Promise that resolves to a session token
when the specified member is approved. Tokens must be approved within 30 hours of token creation.
A new member's status is "PENDING"
when the site's membership policy is set to manual approval.
To learn more about setting your site's membership approval policy, see
Editing Your Member Signup Settings.
Use the approvalToken parameter returned from the
register()
function when calling approveByToken().
Approval token returned by the register() function.