refactor: optimisation around stoptimes

- moved stoptime related functionality into new core:data:stoptime module
  - will feature all the different realtime stoptime sources to be
      integrated later
- create proper database schema for future migrations
- deduplicate trips into stoppingpatterns, since many trips share the
  exact same stopping pattern
  - stoptimes are now linked to stoppingpatterns instead
  - stoppingpattern ids are generated from a hash composed of all stoptimes
- stoptimes now use deltas for arrival time to save space

core/sqld/build.gradle.kts

@@ -47,6 +47,7 @@ sqldelight {
     databases {
         register("BanksiaDatabase") {
             packageName.set("moe.lava.banksia.core.sqld")
+            schemaOutputDirectory.set(file("src/commonMain/sqldelight/schema"))
         }
     }
 }