Ingest different DRS formats

This PR is a significant rewrite of how we handle DRS file paths to allow us to ingest paths of a few different known DRS formats.

This involved:

• creating a new crate to handle just loading the different DRS types
• changing ingestion to load the different types and then convert them to our metadata format
• fix some funky issues with data-dir not behaving how it should
  • I also made it optional so not having it means that all datasets are ingested

drs/src/parser/cordex.rs

@@ -22,7 +22,7 @@ pub(crate) fn parse_cordex(i: &str) -> IResult<&str, PathMetadata> {
     /*
     <activity>/<product>/<domain>/<institution>/
     <gcm_model_name>/<cmip5_experiement_name>/<cmip5_ensemble_member>/
-    <rcm_model_name>/<rcm_version_id>/<frequency>/<variable_name>
+    <rcm_model_name>/<rcm_version_id>/<frequency>/<variable_name>/[<version>/]
     */
     let (i, activity) = path_segment(i)?;
     let (i, product) = path_segment(i)?;