Allow the remind interval for the admin email verification to be filtered

[desrosj]

The admin email verification screen's display interval can be filtered using admin_email_check_interval, but the remind me later interval is hard coded at 3 days.

It would be great to allow this to be filtered. This could also be used to disable the Remind me later link by returning a "falsey" value (similar to how admin_email_check_interval works). A use case I can think of is a site that only wants to allow the admins to "snooze" the page X number of times before having to actually confirm the email.

[desrosj]

Add filter for remind interval and hide the Remind me later link if a falsey value is returned.

[Clorith]

This looks good, and I'd like to see it come in alongside #48333 for consistency, so I'm marking this for 5.3.1 along with it.

[birgire]

In the filter's description of the admin_email_check_interval we have the 0 case (falsey) explained:

   /**
     * Filters the interval for redirecting the user to the admin email confirmation screen.
     * If `0` (zero) is returned, the user will not be redirected.
     *
     * @since 5.3.0
     *
     * @param int Interval time (in seconds).
     */

I suggest we also explain the zero (falsey) case for the admin_email_remind_interval filter.

Eg. change from:

/**
 * Filters the interval for dismissing the admin email confirmation screen.
 *
 * @since 5.3.0
 *
 * @param int Interval time (in seconds). Default is 3 days.
 */
 $remind_interval = (int) apply_filters( 'admin_email_remind_interval', 3 * DAY_IN_SECONDS );

to

/**
 * Filters the interval for dismissing the admin email confirmation screen.
 * If `0` (zero) is returned, the "Remind me later" link will not be displayed.
 *
 * @since 5.3.1
 *
 * @param int Interval time (in seconds). Default is 3 days.
 */
 $remind_interval = (int) apply_filters( 'admin_email_remind_interval', 3 * DAY_IN_SECONDS );

or something similar about the reminder functionality being disabled.

[SergeyBiryukov]

In 46838:

Users: Introduce admin_email_remind_interval filter for dismissing the admin email confirmation screen.

Props desrosj, birgire.
Fixes #48334.

[SergeyBiryukov]

In 46839:

Users: Introduce admin_email_remind_interval filter for dismissing the admin email confirmation screen.

Props desrosj, birgire.
Merges [46838], [46837] to the 5.3 branch.
Fixes #48334.