include /cog endpoints in titiler-pgstac by default

This issue may belong in titiler-pgstac, but one thing that would make the default eoapi-cdk deployment even better would be to include the `/cog` endpoints from `titiler`. @jjfrench is working on [consolidating our `titiler` deployments](https://github.com/NASA-IMPACT/active-maap-sprint/issues/988) over in MAAP and one thing that is preventing us from running everything on a single `titiler-pgstac` deployment is the `/cog` endpoints which are available in an old `titiler` deployment but not in the `eoapi` deployment. It can be useful to be able to use the `/cog` endpoints to inspect data *before* it is cataloged in a STAC item. Maybe it would be better described by a set of `/external` endpoints to use for data that is not in the STAC yet. I'm not sure but I think there has been a similar discussion in VEDA cc @wildintellect.

It would be pretty simple to add to the `handler.py` in this repo or in `titiler.pgstac.main.app`. A user *could* customize eoapi to add these endpoints but it might also make sense to include that set of endpoints by default.