Migrated category module from Java to Kotlin (#6016)

* Rename .java to .kt

* Rebased category PR

* Resolved conflicts

---------

Co-authored-by: Nicolas Raoul <[email protected]>

Author: Saifuddin53

app/src/main/java/fr/free/nrw/commons/category/CategoriesModel.kt

@@ -78,7 +78,13 @@ class CategoriesModel
 
             // Newly used category...
             if (category == null) {
-                category = Category(null, item.name, item.description, item.thumbnail, Date(), 0)
+                category = Category(
+                    null, item.name,
+                    item.description,
+                    item.thumbnail,
+                    Date(),
+                    0
+                )
             }
             category.incTimesUsed()
             categoryDao.save(category)

app/src/main/java/fr/free/nrw/commons/category/Category.java

@@ -0,0 +1,17 @@
+package fr.free.nrw.commons.category
+
+import android.net.Uri
+import java.util.Date
+
+data class Category(
+    var contentUri: Uri? = null,
+    val name: String? = null,
+    val description: String? = null,
+    val thumbnail: String? = null,
+    val lastUsed: Date? = null,
+    var timesUsed: Int = 0
+) {
+    fun incTimesUsed() {
+        timesUsed++
+    }
+}

app/src/main/java/fr/free/nrw/commons/category/Category.kt

@@ -0,0 +1,5 @@
+package fr.free.nrw.commons.category
+
+interface CategoryClickedListener {
+    fun categoryClicked(item: CategoryItem)
+}