add tests for pair style colloid in variants in several neighbor list and comm variants

this does 3 tests:
- regular neighborlist binning with single cutoff communication
- comm style brick with multi-cutoff neighborlists and communication
- comm style tiled with multi-cutoff neighborlists and communication

unittest/force-styles/tests/in.colloid

@@ -0,0 +1,16 @@
+variable  newton_pair     index  on
+variable  newton_bond     index  on
+variable  units           index  lj
+variable  input_dir       index  .
+variable  data_file       index ${input_dir}/data.colloid
+variable  pair_style      index 'zero 8.0'
+
+atom_style       atomic
+atom_modify      map array
+neigh_modify     delay 2 every 2 check no
+timestep         0.01
+units            ${units}
+newton           ${newton_pair} ${newton_bond}
+
+pair_style       ${pair_style}
+read_data        ${data_file}