petascope - add SECORE as embedded inside petascope

[Bang Pham Huu]

1. enable embedding secore into petascope as a library jar (internal secore)
2. retain ability to work as a standalone webapp as well though, so it can be deployed on its own e.g. at opengis.net (external secore)
3. in petascope.properties, additionally allow internal as a value for secore_urls, e.g. by default they could be

   secore_urls=internal
   

   but if someone wants to add a fallback with potentially more CRS they could add external secore endpoints, e.g.

   secore_urls=internal