Replace CupertinoActivityIndicator with CircularProgressIndicator

[krille-chan]

Description

The app is very material and very cute. For some reason, the CupertinoActivityIndicator is being used at four locations anyway:

• bootstrap_dialog.dart:81
• key_verification_dialog.dart:180
• key_verification_dialog.dart:265
• send_location_dialog.dart:170

I would propose to replace these occurrences by a (material) CircularProgressIndictor in order to provide a more coherent experience.

To Reproduce

(It's not a bug but a feature request...)

grep -R "CupertinoActivityIndicator" /path/to/my/repo

Additional information:

Does not matter.

[github-actions]

This issue is stale because it has been open for 120 days with no activity.

[github-actions]

This issue was closed because it has been inactive for 14 days since being marked as stale.