Add context menu item to copy username *and* password at once

[agowa]

Summary

It would be a huge QoL improvement to have the "copy username and password" option in the context menu. Similar to how Remote Desktop Manager has it.

Examples

Clicking the option will:

1. First copy the username into the clipboard
2. Wait until the clipboard has been accessed/pasted (there must be an event for this, as Remote Desktop Manager also listens for it somehow)
3. Without requiring a 2nd interaction with the KeePassXC GUI automatically copy the password into the clipboard
4. Wait for the configured clipboard timeout and clear it as usual.

Context

Huge QoL improvement when logging into e.g. Libvirt/KVM/QEMU Konsoles or SSH sessions (via password) or having to enter credentials into different places. This is one of the features I miss in KeePassXC that Remote Desktop Manager has.

[droidmonkey]

Wait until the clipboard has been accessed/pasted

There is no way to do this on any platform.

Overall, you need to switch to using auto-type where this is already a feature. Clipboard is definitely not our primary interaction preference and we don't encourage it's use extensively.

[agowa]

Remote Desktop Manager does this on Windows, MacOS, and Linux. Looks quite universal to me. Also Autotype doesn't work with wayland...

/cc @awakecoding

[awakecoding]

We do the successive copy/pasting of the username and password by changing the contents of the clipboard after its been copied a first time. This requires rejecting clipboard managers that automatically copy all clipboard contents immediately as it changes. In other words, we set the clipboard contents to the username, and after it has been copied once, we change it to the password, etc. it's a bit of a hack but it requires less manual user interaction to copy two fields (username and password) separately from the clipboard