adding a basic PDF Viewer implementation

app/src/main/AndroidManifest.xml

@@ -83,6 +83,18 @@
             </intent-filter>
         </activity>
 
+        <activity
+            android:name=".activities.PDFViewerActivity"
+            android:exported="true"
+            android:label="@string/pdf_viewer">
+
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="application/pdf" />
+            </intent-filter>
+        </activity>
+
         <activity
             android:name=".activities.DecompressActivity"
             android:exported="true"

app/src/main/kotlin/com/simplemobiletools/filemanager/pro/activities/PDFViewerActivity.kt

@@ -0,0 +1,16 @@
+package com.simplemobiletools.filemanager.pro.activities
+
+import android.os.Bundle
+import com.simplemobiletools.commons.extensions.checkAppSideloading
+import com.simplemobiletools.filemanager.pro.R
+
+class PDFViewerActivity : SimpleActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_pdf_viewer)
+
+        if (checkAppSideloading()) {
+            return
+        }
+    }
+}

app/src/main/res/layout/activity_pdf_viewer.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/pdf_viewer_wrapper"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content">
+
+</RelativeLayout>