fix(Build.py + CI): add --userdataobj flag; fix lcov path + coverage artifacts

[simonCatBot]

Summary

This PR fixes two issues that currently prevent the OpenVX CI workflow from running successfully:

1. Build.py missing --userdataobj flag (causes CI build failure)

The CI workflow added --userdataobj to the Build.py invocation, but Build.py does not recognize this argument, causing an immediate SystemExit: 2 (unknown option) failure.

Fix: Added --userdataobj option to Build.py that maps to -DOPENVX_USE_USER_DATA_OBJECT=ON.

2. Coverage collection broken in cts-baseline

Two related issues prevented lcov from successfully collecting coverage data:

• Missing build artifacts: The build-debug job only uploaded install/ and include/, but lcov needs the build/Linux/x64/Debug/ tree containing .gcno and .gcda files.
• Wrong lcov working directory: The cts-baseline job runs from inside build-cts/, so the relative path build/Linux/x64/Debug resolves incorrectly.

Fix:

• Added build/Linux/x64/Debug/ to the openvx-debug artifact upload paths.
• Changed lcov directory argument to absolute: ${{ github.workspace }}/build/Linux/x64/Debug.

Related

• Supersedes fix(Build.py): add missing --userdataobj CLI flag #62 and ci: robust CI workflow + fix --userdataobj flag #63 (which had merge conflicts due to amended commits on the same branch).
• Fixes the "Build Release (main)" failure observed in recent CI runs.

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