Add "custom" field in Ticket Attachment Settings --> Maximum File Size

[ework2]

Prerequisites

• [Y] Can you reproduce the problem in a fresh installation of the "develop" branch?
• [N] Do you have any errors in the PHP error log, or javascript console?
• [Y] Did you check the osTicket forums?
• [Y] Did you perform a cursory search to see if your bug or enhancement is already reported?

For more information on how to write a good bug report

Description

Right now Maximum File Size dropdown list is generated by OsTicket and it is not customizable. I would propose to add "custom" value field, so that user could add their own values.
[Description of the bug or feature]

Steps to Reproduce

1. In admin panel navigate to Tickets --> Ticket Attachment Settings.
2. Click on Maximum File Size dropdown

Expected behavior: [What you expected to happen]
Custom value field, where user can add their own custom value.
Actual behavior: [What actually happened]
Dropdown is generated by OsTicket and is not customizable.

Versions

OsTicket version 1.17.2