Check & request operation missing before using accountManager.getAccountsByType()

[aper-project]

Issue description

Hi, in ncsms-android v1.0.0, we found a dangerous API usage (https://github.com/nerzhul/ncsms-android/blob/master/src/main/java/fr/unix_experience/owncloud_sms/activities/remote_account/RestoreMessagesActivity.java#L64) which requires Manifest.permission.GET_ACCOUNTS in accordance to the Android official documentation (https://developer.android.google.cn/reference/android/accounts/AccountManager?hl=en#getAccountsByType(java.lang.String)).

However, it seems that it missed the “check” and “request” operation in the following call chain starting from the RestoreMessagesActivity.onCreate(android.os.Bundle) activity if permission is not granted.

CALLCHAIN:
	fr.unix_experience.owncloud_sms.activities.remote_account.RestoreMessagesActivity.onCreate(android.os.Bundle)void
	 android.accounts.AccountManager.getAccountsByType(java.lang.String)android.accounts.Account[]

This may lead to a SecurityException or related functions unavailable if the user denies the access permission but still calls the API in this chain, resulting in bad user experience.

@nerzhul Could you help me review this issue? Thx