Add theme reloading api

src/main/java/run/halo/app/controller/admin/api/ThemeController.java

@@ -135,4 +135,10 @@ public class ThemeController {
     public ThemeProperty fetchTheme(@RequestParam("uri") String uri) {
         return themeService.fetch(uri);
     }
+
+    @PostMapping("reload")
+    @ApiOperation("Reloads themes")
+    public void reload() {
+        themeService.reload();
+    }
 }

src/main/java/run/halo/app/service/ThemeService.java

@@ -6,7 +6,6 @@ import run.halo.app.handler.theme.config.support.Group;
 import run.halo.app.handler.theme.config.support.ThemeProperty;
 import run.halo.app.model.support.ThemeFile;
 
-import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.List;
@@ -233,4 +232,9 @@ public interface ThemeService {
      */
     @NonNull
     ThemeProperty fetch(@NonNull String uri);
+
+    /**
+     * Reloads themes
+     */
+    void reload();
 }

src/main/java/run/halo/app/service/impl/ThemeServiceImpl.java

@@ -433,6 +433,11 @@ public class ThemeServiceImpl implements ThemeService {
         }
     }
 
+    @Override
+    public void reload() {
+        eventPublisher.publishEvent(new ThemeUpdatedEvent(this));
+    }
+
     /**
      * Clones theme from git.
      *