Fixed checkin/checkout email boolean check for Licenses

[Godmartinz]

Description

UGH. This fixes a checkin/checkout email not being sent for licenses.
The boolean check was failing to fire an email because the checkoutable type is license_seat and license_seat does not have a method of checkin_email to check the category if it should send an email.

Added a method to check the license of the license_seat if it should send an email now.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• [ x] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Test Configuration:

• PHP version:
• MySQL version
• Webserver version
• OS version

Checklist:

• I have read the Contributing documentation available here: https://snipe-it.readme.io/docs/contributing-overview
• I have formatted this PR according to the project guidelines: https://snipe-it.readme.io/docs/contributing-overview#pull-request-guidelines
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[what-the-diff]

PR Summary

• Email Sending Condition Improvement
  The condition that checks when to send an email during the 'checked out' and 'checked in' process has been improved. The process has been simplified and made more readable with the introduction of a new function. This change will make the code easier to understand and maintain.

• New 'checkoutableShouldSendEmail' Method Introduced
  A new function called 'checkoutableShouldSendEmail' has been added. It contains the rules that check if an email should be sent after checking out or in. This method simplifies the condition check and is specifically used when the instance checked out is a LicenseSeat. This compartmentalized approach to handling logic makes the system more robust and reliable.

[marcusmoore]

Phew...good stuff 😄