Add filter to modify expiration time in entry moderation merge tag

[rafaehlers]

A user asked:

is it possible to remove the time limit for the merge tags links?
So it should be available any time, not for 24h.

• If time-limited, make sure the maximum is 48 hours; that's all nonces can support.
• If time is empty (0), remove nonce and use other validation system

And there are no filters here:

GravityView/includes/class-gravityview-entry-approval-merge-tags.php

Line 34 in 3972659

const DEFAULT_EXPIRATION_VALUE = 24;

Related:

• https://docs.gravitykit.com/article/904-entry-moderation-merge-tags
• Add filter to entry moderation merge tag return url #1874

[zackkatz]

FreeScout #71831.
https://support.gravitykit.com/conversation/71831?folder_id=1

[rafaehlers]

Related: #1986