chore: add LLVM/Clang to x86/aarch64 docker image

Add the LLVM/clang toolchains to the 'full' docker image. For x86 Hafnium builds, this permits using an out of tree toolchain rather than relying on the toolchain provided by Hafnium prebuilts submodule. For aarch64 builds, provide the corresponding toolchain as Hafnium doesn't provide such toolchain in prebuilts. Add libncurses dependency required by LLVM/clang toolchain.

Signed-off-by: Olivier Deprez olivier.deprez@arm.com Reviewed-by: Ryan Roberts ryan.roberts@arm.com