Shift+return was always inserting newline at the end of the current line of text, ignoring where the cursor was, and not overriding currently selected text
BUG: 488585
Directly calling signals is the supported way to send signals.
Calling signal handlers worked in the past, but will be phased out in
the future (https://bugreports.qt.io/browse/QTBUG-120573).
The "enabled" property of the button was set to false and has overwritten the default value based on the message length.
The message field had "anchors.fill" positioning and raised "Binding loop detected for property "implicitHeight"" error.
attachmentList property of ChatMessage didn't have the default value and was undefined.
BUG: 455149
Use a singleton instead of context properties for data handling
Fix passing initial message
Make device menu creation more declarative
Fix initial device handling
Update current device when new instance with initial device is requested
- Move the device combobox to the global drawer
- Move search field and new button to header
- Use Kirigami SearchField instead
- Don't switch focus away from search field when typing
- Give the New button an icon
- Clarify the search field text
- Center messages view loading indicator
- Make send and attach buttons stick to bottom of text area
- Make cursor an I-beam when hovering over text area
- Move send button to the right
- Give proper padding to messages view top
- Move refresh action to global drawer
- Show refresh button directly in loading message where it is most useful
| Before | After |
| ------ | ------ |
|  |  |
|  |  |
|  |  |
cc @teams/usability @teams/vdg
## Summary
Replace the (deprecated and removed) reference to `Kirigami.Theme.viewBackgroundColor` with `Kirigami.Theme.backgroundColor`
This element is necessary in order to have theme hot-switching work correctly
BUG 434791
## Test Plan
### Before:
When using the KDE Connect SMS app in an un-modified dark theme, the message entry text box would be rendered as all white and text would correctly be rendered in white (making it un-readable).
This seems to be somehow related to a recent Kirigami version (it only happened to me after doing a distro upgrade and my ancient Kirigami installed to ~/.prefix does not reproduce the issue).
viewBackgroundColor was deprecated and apparently removed from Kirigami a version or two ago. Thus the coloring was no longer correct.
For screenshots and discussion, see [bug 434791](https://bugs.kde.org/show_bug.cgi?id=434791)
### After:
Text and background are rendered in the expected colours for the theme.
