fix: line number support for unity 6.5 and newer

[bitsandfoxes]

Context

In Unity 6.3 and older, when building the game you'd end up with an output folder looking like that

.
├── game-name_BackUpThisFolder_ButDontShipItWithYourGame
│   ├── GameAssembly.dSYM
│   ├── il2cppOutput
│   └── Managed
|        ├ all-the-dlls.dll
|        └ all-the-dlls.pdb
└── game-name.app

The Managed directory would contain all the stripped down .dll and matching .pdb files. Starting with 6.5 the Managed folder contains the .dll only. To get to the .pdb you will need to do a Development build and opt-in to Script Debugging. Not ideal.

What this does

These options provide the UnityLinker with the additional argument --link-symbols.

So starting with Unity 6.5 on top of adding --emit-source-mapping to IL2CPP we need to add this argument when the UnityLinker gets invoked. Since there are no callbacks and the backdoor of AdditionalIl2CppArguments only works for IL2CPP we're putting it on the environment in the pre-build-step to be picked up.

We'll need to find a less brittle way of getting to the debug symbols

Before

After

Testing

We're now also validating that the stack trace on the resulting events coming from the integration tests do have correct line numbers.

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[sentry]

Bug: The test skip condition checks for $script:Platform being "Linux", but for Linux builds, it's set to "Desktop". This causes a test to run when it should be skipped.
_{Severity: MEDIUM}

Suggested Fix

Update the skip condition to correctly identify the Linux environment. Since Linux builds set $script:Platform to "Desktop", the condition should be modified to account for this. For example, you could check if $IsLinux is true when $script:Platform is "Desktop", or adjust the platform value assignment in integration-test.ps1.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: test/IntegrationTest/Integration.Tests.ps1#L352-L354

Potential issue: The test skip condition `if ($script:Platform -in "WebGL", "Linux")` is
intended to prevent a line number assertion test from running on Linux. However, the
build script sets `$script:Platform` to "Desktop" for Linux environments. As a result,
the condition is never met on Linux, and the test proceeds to run. This test is expected
to fail on Linux because the `--link-symbols` feature, which is necessary for correct
line number resolution, is not supported. This will cause the CI pipeline to fail for
Linux builds, contrary to the author's intent to exclude Linux from this specific test.