Fix diagnostic locations for inherited bicepparam values

[polatengin]

Description

Fixes #19982.

Type diagnostics for parameter values inherited from an extended .bicepparam file were generated using spans from the parent file, but published against the child file. This caused diagnostics to appear on unrelated text, such as the using or extends declarations.

This change re-anchors diagnostics for inherited parameter values to the child file's extends path while preserving their original code, message, and severity.

I've added integration tests to improve coverage for different scenarios.

Checklist

• I have read and adhere to the contribution guide.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 30045701207)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 30045701207

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 30045701207"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 30045701207

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 30045701207"