Cling CI matrix proposed

--------------------------CI-------------------------------

OS: ubuntu-16.04
compiler: gcc
compiler-version: 7
Python: 3.8
from-llvm-binary: package-manager
cpt: yes

OS: ubuntu-16.04
compiler: gcc
compiler-version: 7
Python: 3.8
from-llvm-binary: tarball
cpt: yes

OS: ubuntu-16.04
compiler: gcc
compiler-version: 7
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-16.04
compiler: clang
compiler-version: 7
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-18.04
compiler: clang
compiler-version: 7
Python: 3.8
from-llvm-binary: package-manager
cpt: yes

OS: ubuntu-18.04
compiler: clang
compiler-version: 7
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-18.04
compiler: gcc
compiler-version: 7
Python: 3.8
from-llvm-binary: package-manager
cpt: yes

OS: ubuntu-18.04
compiler: gcc
compiler-version: 7
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: clang
compiler-version: 7
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 7
Python: 2.7
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 4.8
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 5
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 6
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 7
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 8
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 9
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: ubuntu-20.04
compiler: gcc
compiler-version: 7
Python: N/A
from-llvm-binary: no (compile from source)
cpt: no

OS: macOS-latest
compiler: gcc
gcc-version: 9
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: macOS-latest
compiler: gcc
gcc-version: 9
Python: N/A
from-llvm-binary: no (compile from source)
cpt: no

OS: macOS-latest
compiler: clang
xcode-version: 11.2.1
Python: 3.8
from-llvm-binary: no (compile from source)
cpt: yes

OS: macOS-latest
compiler: clang
xcode-version: 11.2.1
Python: N/A
from-llvm-binary: no (compile from source)
cpt: no

OS: macOS-latest
compiler: clang
xcode-version: 11.2.1
Python: 3.8
from-llvm-binary: tarball
cpt: yes

OS: macOS-latest
compiler: clang
xcode-version: 11.2.1
Python: 2.7
from-llvm-binary: tarball
cpt: yes

OS: windows-2019
generator: Ninja
Python: 3.8
cpt: yes

OS: windows-2019
generator: Ninja
Python: 2.7
cpt: yes

OS: windows-2019
generator: Visual Studio
Python: 3.8
cpt: yes

OS: windows-2019
generator: Ninja
Python: N/A
cpt: no

OS: windows-2019
generator: Visual Studio
Python: N/A
cpt: no

--------------------------CD-------------------------------

OS: macOS-latest
format: tarball

OS: ubuntu-20.04
format: deb

OS: ubuntu-20.04
format: tarball