Fix/add data removing option

[sapayth]

In User Frontend > Tools a new setting is introduced to delete some data upon plugin deletion. When you delete the WP User Frontend version, it will also delete all the data related to WP User Frontend Pro as well. This won't happen when the plugins are deactivated.

1. Delete Plugin Settings on Uninstall
2. Delete Database Tables on Uninstall
3. Delete WPUF Forms on Uninstall
4. Delete WPUF Pages on Uninstall

Settings that will be removed are:
all options containing wpuf_

DB tables that will be removed are:

1. wpuf_transaction
2. wpuf_subscribers
3. wpuf_message
4. wpuf_activity

All pages containing wpuf shortcode

[Rat01047]

Issue:
Cannot Sign-In into Admin after deleting Plugin with options activated via Tools

Scenario:
WPUF > Tools > Clicked all the Options built in this PR > Deleted Plugin > Cannot access Admin Dashboard

[sapayth]

Issue: Cannot Sign-In into Admin after deleting Plugin with options activated via Tools

Scenario: WPUF > Tools > Clicked all the Options built in this PR > Deleted Plugin > Cannot access Admin Dashboard

Seems ok from my end. Would you please test again?

[Rat01047]

Issue: Cannot Sign-In into Admin after deleting Plugin with options activated via Tools
Scenario: WPUF > Tools > Clicked all the Options built in this PR > Deleted Plugin > Cannot access Admin Dashboard

Seems ok from my end. Would you please test again?

Still exists, when you select all the options and then Delete the Plugin

[Rat01047]

@sapayth the issue still exists, selecting all the settings given in PR and then uninstalling plugin > takes away admin's ability to access site

Screenshot for reference:
https://tinyurl.com/yrtfx389