Move bisq.core{=>.app}.CoreModule

There are two structural / organizational reasons for this move:

 1. References from one package to another should always be upward or
 lateral, never downward, as the latter causes package cycles (aka
 'tangles') which damage the suppleness and understandability of a large
 codebase. Prior to this change the high-level bisq.core.CoreModule
 class imported many classes from child packages like
 bisq.core.{btc,dao,user,util}, etc. By moving CoreModule down into the
 '.app' package, it can reference all these other packages as siblings
 instead of doing so as a parent.

 2. the bisq.core.desktop and bisq.core.app packages are the only
 locations that reference the CoreModule class. By moving the class
 into bisq.core.app, greater cohesion is acheived, again making the
 codebase that much easier to read and understand.

core/src/main/java/bisq/core/app/BisqHeadlessAppMain.java

@@ -17,8 +17,6 @@
 
 package bisq.core.app;
 
-import bisq.core.CoreModule;
-
 import bisq.common.UserThread;
 import bisq.common.app.AppModule;
 import bisq.common.app.Version;

core/src/main/java/bisq/core/app/CoreModule.java

@@ -15,11 +15,9 @@
  * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
  */
 
-package bisq.core;
+package bisq.core.app;
 
 import bisq.core.alert.AlertModule;
-import bisq.core.app.AppOptionKeys;
-import bisq.core.app.BisqEnvironment;
 import bisq.core.btc.BitcoinModule;
 import bisq.core.dao.DaoModule;
 import bisq.core.filter.FilterModule;

desktop/src/main/java/bisq/desktop/app/BisqAppModule.java

@@ -19,7 +19,7 @@ package bisq.desktop.app;
 
 import bisq.desktop.DesktopModule;
 
-import bisq.core.CoreModule;
+import bisq.core.app.CoreModule;
 
 import bisq.common.app.AppModule;
 

grpc/src/main/java/bisq/grpc/BisqGrpcServerMain.java

@@ -18,10 +18,10 @@
 package bisq.grpc;
 
 import bisq.core.CoreApi;
-import bisq.core.CoreModule;
 import bisq.core.app.BisqExecutable;
 import bisq.core.app.BisqHeadlessAppMain;
 import bisq.core.app.BisqSetup;
+import bisq.core.app.CoreModule;
 
 import bisq.common.UserThread;
 import bisq.common.app.AppModule;