Convert auth package to kotlin (#5966)

* Convert SessionManager to kotlin along with other small fixes

* Convert WikiAccountAuthenticator to kotlin

* Migrate WikiAccountAuthenticatorService to kotlin

* Converted AccountUtil to kotlin

* Convert SignupActivity to kotlin

* Convert LoginActivity to kotlin

* Merge from main

app/src/androidTest/java/fr/free/nrw/commons/ui/PasteSensitiveTextInputEditTextTest.kt

@@ -17,7 +17,7 @@ class PasteSensitiveTextInputEditTextTest {
     @Before
     fun setup() {
         context = ApplicationProvider.getApplicationContext()
-        textView = PasteSensitiveTextInputEditText(context)
+        textView = PasteSensitiveTextInputEditText(context!!)
     }
 
     // this test has no real value, just % for test code coverage

app/src/main/java/fr/free/nrw/commons/auth/AccountUtil.kt

@@ -0,0 +1,24 @@
+package fr.free.nrw.commons.auth
+
+import android.accounts.Account
+import android.accounts.AccountManager
+import android.content.Context
+import androidx.annotation.VisibleForTesting
+import fr.free.nrw.commons.BuildConfig.ACCOUNT_TYPE
+import timber.log.Timber
+
+const val AUTH_TOKEN_TYPE: String = "CommonsAndroid"
+
+fun getUserName(context: Context): String? {
+    return account(context)?.name
+}
+
+@VisibleForTesting
+fun account(context: Context): Account? = try {
+    val accountManager = AccountManager.get(context)
+    val accounts = accountManager.getAccountsByType(ACCOUNT_TYPE)
+    if (accounts.isNotEmpty()) accounts[0] else null
+} catch (e: SecurityException) {
+    Timber.e(e)
+    null
+}