Generate Kiwix app bundle via CI to upload manually on play store.

[MohitMaliFtechiz]

Describe the bug
For issue #4026 we have to manually upload the application on playStore, so we need an app bundle to upload on playStore. Currently, there is only one way to generate an app bundle which is manually generating through the "Android Studio" but for this, we need keystore and key password(Also, need manual steps to generate the app bundle). But it should be done via the CI like we are doing for custom apps.