Add top-level attributes for hg, svn, and git A-L packages

var/spack/repos/builtin/packages/accfft/package.py

var/spack/repos/builtin/packages/adios/package.py

var/spack/repos/builtin/packages/adios2/package.py

var/spack/repos/builtin/packages/adol-c/package.py

var/spack/repos/builtin/packages/albany/package.py

var/spack/repos/builtin/packages/alquimia/package.py

var/spack/repos/builtin/packages/amg/package.py

var/spack/repos/builtin/packages/amp/package.py

var/spack/repos/builtin/packages/amrex/package.py

var/spack/repos/builtin/packages/amrvis/package.py

var/spack/repos/builtin/packages/arpack-ng/package.py

var/spack/repos/builtin/packages/ascent/package.py

var/spack/repos/builtin/packages/aspa/package.py

var/spack/repos/builtin/packages/aspect/package.py

var/spack/repos/builtin/packages/axl/package.py

var/spack/repos/builtin/packages/bash-completion/package.py

var/spack/repos/builtin/packages/bbcp/package.py

var/spack/repos/builtin/packages/benchmark/package.py

var/spack/repos/builtin/packages/biopieces/package.py

var/spack/repos/builtin/packages/bml/package.py