Stores the password reset redirect_to URL.
When the user clicks the password reset on the LD login popup we capture the ‘redirect_to’ URL. This is done at step 2 of the password reset process after the user has enter their username/email.
The user will then receive an email from WP with a link to reset the password. Once the user has created a new password they will be shown a login link. That login URL will be the stored ‘redirect_to’ user meta value. See the function learndash_password_reset_login_url() for that stage of the processing.