[ANR] RealmKeysUtils.configureEncryption

Looks like `SecretStoringUtils.rsaDecrypt` should be executed off of the main thread

```
at com.android.org.conscrypt.NativeCrypto.RSA_private_decrypt (Native method)
at com.android.org.conscrypt.OpenSSLCipherRSA.engineDoFinal (OpenSSLCipherRSA.java:273)
at com.android.org.conscrypt.OpenSSLCipherRSA.engineDoFinal (OpenSSLCipherRSA.java:297)
at javax.crypto.Cipher.doFinal (Cipher.java:1314)
at javax.crypto.CipherInputStream.fillBuffer (CipherInputStream.java:102)
at javax.crypto.CipherInputStream.read (CipherInputStream.java:155)
at org.matrix.android.sdk.internal.session.securestorage.SecretStoringUtils.rsaDecrypt (SecretStoringUtils.kt:4)
at org.matrix.android.sdk.internal.session.securestorage.SecretStoringUtils.decryptString (SecretStoringUtils.kt:2)
at org.matrix.android.sdk.internal.database.RealmKeysUtils.getRealmEncryptionKey (RealmKeysUtils.kt:10)
at org.matrix.android.sdk.internal.database.RealmKeysUtils.configureEncryption (RealmKeysUtils.kt:1)
at org.matrix.android.sdk.internal.util.TemporaryFileCreator_Factory.get (TemporaryFileCreator_Factory.java:43)
at dagger.internal.DoubleCheck.get (DoubleCheck.java:5)
at org.matrix.android.sdk.internal.session.DefaultSession_Factory.get (DefaultSession_Factory.java:1)
at dagger.internal.DoubleCheck.get (DoubleCheck.java:5)
at org.matrix.android.sdk.internal.session.DaggerSessionComponent.session (DaggerSessionComponent.java:1)
at org.matrix.android.sdk.internal.auth.DefaultAuthenticationService.getLastAuthenticatedSession (DefaultAuthenticationService.kt:3)
at im.vector.app.VectorApplication.onCreate (VectorApplication.kt:109)
```