Update Docker file for package-based LLVM/Clang install

[abeltrano]

Type

• Bug fix
• Feature addition
• Feature update
• Documentation
• Build Infrastructure

Side Effects

• Breaking change
• Non-functional change

Goals

• Minimize Docker image build time and simplify server controller setup, taking advantage of LLVM and Clang 17 now being available in the main package repository for Ubuntu 23.10 mantic.

Technical Details

• Replace manual llvm installation script with use of clang-*-17 and llvm-*-17 packages.
• Update Linux README for how to set up a development machine using package-based LLVM+Clang installation.
• Fix fenced code appearing in lists in Linux README.
• Replace use of apt-get <command> with apt <command>.
• Ad apt upgrade to bring packages to newest versions.

Test Results

• Built and published both docker images netremote-build and netremote-dev` on Windows.
• Set up a new server afresh, followed the Linux README instructions by copy-and-pasting the commands, then pulled and built the project successfully.

Reviewer Focus

• None

Future Work

• None

Checklist

• Build target all compiles cleanly.
• clang-format and clang-tidy deltas produced no new output.
• Newly added functions include doxygen-style comment block.