Fix Dockerfile

[Yarroudh]

This PR fixes the Docker build errors by addressing two root causes:

1. libpcl-dev not found

• Enabled the universe repository before installing dependencies, ensuring libpcl-dev is available on Ubuntu 20.04.
• Added apt-get update after enabling the repo to refresh package lists.

2. install_dependencies.bash CRLF issues

• Added a step to normalize line endings from CRLF to LF using sed, preventing $'\r': command not found errors.
• Made script files executable before running them to avoid permission issues.

3. Build the App

• Copied project sources into /workspace and ran a CMake out-of-source build.

• Enabled example/app targets (-DBUILD_EXAMPLES=ON -DBUILD_APPS=ON) so 3d_line_detection_app is produced.

• Added a fallback to build the target directly if a full build fails:

  cmake -S . -B build -DBUILD_EXAMPLES=ON -DBUILD_APPS=ON
  cmake --build build -j"$(nproc)" || cmake --build build --target 3d_line_detection_app -j"$(nproc)"

Additional changes

• Set DEBIAN_FRONTEND=noninteractive as an ENV for consistency across layers.
• Consolidated apt commands to keep layers small and cache-friendly.