Fix Linux installer NetworkManager file URIs

[Game4Move78]

Summary

Fix the Linux installer template so NetworkManager file URI settings are sent as plain length-delimited D-Bus byte arrays instead of NUL-terminated strings.

Problem

The generated Linux installer currently serializes ca-cert, client-cert, and private-key as dbus.ByteArray(b"file://...\0").
On newer NetworkManager setups this can persist as a %00 suffix in the stored path, which breaks TLS validation during 802.1X authentication.

Changes

• add a small helper in devices/linux/Files/main.py to build NetworkManager file URI byte arrays without a trailing NUL
• use that helper for ca-cert, client-cert, and private-key
• add a PHPUnit regression test that checks the Linux template no longer contains the old NUL-terminated patterns

Testing

• regression test added in tests/unit/devices/linux/Files/MainPyTemplateTest.php

[Copilot]

Pull request overview

This PR fixes the Linux installer template’s NetworkManager 802.1X file URI serialization to use length-delimited D-Bus byte arrays (no trailing NUL), preventing persisted paths with a \0 suffix that can break TLS validation.

Changes:

• Add __nm_file_uri() helper to build NetworkManager file URI dbus.ByteArray values without NUL termination.
• Use the helper for ca-cert, client-cert, and private-key settings.
• Add a PHPUnit regression test ensuring the template no longer contains the NUL-terminated patterns.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
devices/linux/Files/main.py	Introduces __nm_file_uri() and updates NM settings to avoid NUL-terminated file URI byte arrays.
tests/unit/devices/linux/Files/MainPyTemplateTest.php	Adds regression coverage by asserting the template contains the helper and omits the old \0-terminated patterns.

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[Copilot]

file_get_contents() can return false if the relative path changes or the file is missing, which would cause a type error in the subsequent assertString* calls and make the test failure harder to diagnose. Consider asserting the file exists and/or that $template !== false before running string assertions (and optionally include a failure message with the resolved path).