Clipboard allows viewing sensitive data when opening up clipboard screen

[Inhishonor]

This bug was reported upstream, but was reclassified as a feature request. Either way, I think it could be good to have in Graphene.

Steps to Reproduce

• Copy something from a password manager.
• The dialog comes up and observe that is asterisks, click on the dialog.
• The clipboard screen has the plain text exposed.

You can also reproduce it, by copying a password, and then going to a text input field and observe that the password is shown in the suggestions bar.

Additional Context

The upstream issue report: https://issuetracker.google.com/issues/429647151

[Inhishonor]

I submitted a pull request that fixes this: GrapheneOS/platform_frameworks_base#249