Incorrect parsing of 0 values in PDF templates

[SinergiaCRM]

Issue

PDF templates do not correctly parse 0 values, because they are interpreted as "empty" or false, and do not show any value in the generated PDF document.
If a dropdown list uses 0 as an internal value, the corresponding label will not be displayed for the same reason.

Expected Behavior

If a value is set to 0 it should display as 0 in the PDF template.

Steps to Reproduce

1. In study create a field of type int in the Accounts module and call it "amount"
2. Include the field in the edit view and modify a record set it to 0
3. Create a PDF template for the Accounts module including in the body of the template "$accounts_amount_c"
4. Generate the PDF document for the modified record and see how the value is not displayed.
5. In the same record, change the value 0 to any other, regenerate the document and verify that it is generated.
6. You can repeat the test using a dropdown list that has any of the values set to 0

Context

In some cases it is necessary to show in the PDF templates the explicit value 0

Your Environment

• SuiteCRM Version used: 7.12.6
• Browser name and version (e.g. Chrome Version 51.0.2704.63 (64-bit)): Chrome Versión 104.0.5112.101 (Build oficial) (64 bits)
• Environment name and version (e.g. MySQL, PHP 7): MariaDB 10, PHP 7.4
• Operating System and version (e.g Ubuntu 16.04): Ubuntu 20.4