Migrated filepicker from Java to Kotlin (commons-app#5997)

* Rename .java to .kt

* Migrated filepicker module from Java to Kotlin

* Rename .java to .kt

* Migrated filepicker module from Java to Kotlin

* fix: test cases

Author: Saifuddin53

app/src/main/java/fr/free/nrw/commons/filepicker/Constants.java

@@ -0,0 +1,29 @@
+package fr.free.nrw.commons.filepicker
+
+interface Constants {
+    companion object {
+        const val DEFAULT_FOLDER_NAME = "CommonsContributions"
+    }
+
+    /**
+     * Provides the request codes for permission handling
+     */
+    interface RequestCodes {
+        companion object {
+            const val LOCATION = 1
+            const val STORAGE = 2
+        }
+    }
+
+    /**
+     * Provides locations as string for corresponding operations
+     */
+    interface BundleKeys {
+        companion object {
+            const val FOLDER_NAME = "fr.free.nrw.commons.folder_name"
+            const val ALLOW_MULTIPLE = "fr.free.nrw.commons.allow_multiple"
+            const val COPY_TAKEN_PHOTOS = "fr.free.nrw.commons.copy_taken_photos"
+            const val COPY_PICKED_IMAGES = "fr.free.nrw.commons.copy_picked_images"
+        }
+    }
+}

app/src/main/java/fr/free/nrw/commons/filepicker/Costants.kt

@@ -0,0 +1,12 @@
+package fr.free.nrw.commons.filepicker
+
+/**
+ * Provides abstract methods which are overridden while handling Contribution Results
+ * inside the ContributionsController
+ */
+abstract class DefaultCallback: FilePicker.Callbacks {
+
+    override fun onImagePickerError(e: Exception, source: FilePicker.ImageSource, type: Int) {}
+
+    override fun onCanceled(source: FilePicker.ImageSource, type: Int) {}
+}

app/src/main/java/fr/free/nrw/commons/filepicker/DefaultCallback.java

@@ -0,0 +1,5 @@
+package fr.free.nrw.commons.filepicker
+
+import androidx.core.content.FileProvider
+
+class ExtendedFileProvider: FileProvider() {}