unify ap_ap10 and apD10_ap_*

We had some duplicate lemmas in `PathGroupoids.v`: `ap_ap10` and `ap_ap10_L` were essentially the same as `apD10_ap_postcompose` and `apD10_ap_precompose`.  Moreover, the latter were not stated in the appropriate dependent generality for their names.  This commit generalizes them and defines corresponding non-dependent versions `ap10_ap_*`.  It is on top of #448 (which uses them) and part of #440 (since it uses `composeD`).