Fix missing messages after import on Android 14 due to subscriptionId

[tom93]

What is it?

• [x] Bugfix
• [ ] Feature
• [ ] Codebase improvement

Description of the changes in your PR

On Android 14, imported messages are not visible if their subscriptionId[1] does not correspond to one of the SIMs in the device. As a workaround, we set subscriptionId to -1 ("unknown") on all messages during import.

This does mean that when exporting then importing on the same device, the SIM associations will be lost. But that doesn't seem noticeable.

Credit: SMS Import / Export app, https://www.github.com/tmo1/sms-ie/issues/128

[1] https://developer.android.com/identity/user-data-ids#mobile-subscription-status

Fixes the following issue(s)

• Fixes #191.

Acknowledgement

• [x] I read the contribution guidelines.