fix: migration of all v2 fixes of the order guest module

See merge request !39

This commit addresses two main issues in `EventHandler.php`.
Firstly, the fetching of the email from the `GuestOrder` session is moved at a different location
in the flow where it makes more sense and doesn't get overridden prematurely.

Secondly, an exhaustive condition handling has been added to address cases where there might be a
payment error or async payment error. The method fetches the current order via the URL hash which
could be an `OrderInProcess` or an already existing `Order`.

The commit also ensures that the customer UUID is set correctly if the session exists. An update is
made to the database to accommodate this change.

Minor changes have also been made to spacing and data-type declaration in `GuestOrderUser.php` to
help with readability and consistency.

Related: #11

fix: logout function for GuestOrderUser -> destroys session

See merge request !33

A new method named 'logout' has been added to the GuestOrderUser class in the directory
src/QUI/ERP/Order/Guest. This function is responsible for destroying the current session.

Related: #10

Next 1.x

See merge request !31

fix: missing isCompany implementation for guest order

See merge request !27

fix: price factors were lost

See merge request !26

Related: brassberg/tickets#242

fix: make it only with quiqqer v1 compatible

See merge request !19

feat: guest login use no longer an event to display guest button in order process

See merge request !21

Related: template-cologne#111

Next 1.x

See merge request !18

fix: user creatoin at async payment

See merge request !15

Next

Closes #5

See merge request !12

Dev

See merge request !11

Next

See merge request !10

Dev

See merge request !9

Next

See merge request !8

Dev

See merge request !7

Next

See merge request !6

fix: use of smarty3 collection class

See merge request !5

feat: new settings

See merge request !4

refactor: code style

See merge request !3