Add C & C++ compiler to workspace default image

MR: Add gcc to workspace default image (gitlab-build-images!945 - merged)

Description

Add C & C++, and Clang, make, cmake to workspace default image, so the default image could support more needs.

Based on checking the code base, Clang, make and cmake are installed in scripts/install-essentials. And we just need to add C and C++ compiler, and conan as package manager.

Acceptance criteria

• Add script scripts/install-c for Ubuntu image, using custom build; ideally we should be be able to specify the specific version to install; install conan as package manager
• enable scripts/install-c in Dockerfile.custom and scripts/lib/custom-docker-build
• Add proper workspace default image job variable

Implementation plan

example code with wget

wget http://ftp.gnu.org/gnu/gcc/gcc-11.1.0/gcc-11.1.0.tar.gz
tar -xvzf gcc-11.1.0.tar.gz
cd gcc-11.1.0
./configure --enable-languages=c,c++
make -j$(nproc)
sudo make install