Refactor input stuff

This is the start of a significant refactoring of everything related to sending messages, which is roughly:
- the chatbox
- action handling
- message sending on the c++ side
- autocompletion of users/rooms/emojis/commands/things i forgot

Notable changes so far include:
- ChatBox is now a ColumnLayout. As part of this, i removed the height animations for now. <del>as far as i can tell, they were broken anyway.</del> I'll readd them later
- Actions were refactored to live outside of the message sending function and are now each an object; it's mostly a wrapper around a function that is executed when the action is invoked
- Everything that used to live in ChatBoxHelper is now in NeoChatRoom; that means that the exact input status (text, message being replied to, message being edited, attachment) is now saved between room switching).
- To edit/reply an event, set `NeoChatRoom::chatBox{edit,reply}Id` to the desired event id, `NeoChatRoom::chatBox{reply,edit}{User,Message}` will then be updated automatically
- Attachments behave equivalently with `NeoChatRoom::chatBoxAttachmentPath`
- Error message reporting from ActionsHandler has been fixed (same fix as in !517) and moved to NeoChatRoom


Broken at the moment:
- [x] Any kind of autocompletion
- [x] Mentions
- [x] Fancy effects
- [x] sed-style edits
- [x] last-user-message edits and replies
- [x] Some of the actions, probably
- [x] Replies from notifications
- [x] Lots of keyboard shortcuts
- [x] Custom emojis
- [x] ChatBox height animations

TODO:
- [x] User / room mentions based on QTextCursors instead of the hack we currently use
- [x] Refactor autocompletion stuff
- [x] ???
- [x] Profit

src/CMakeLists.txt

@@ -30,8 +30,6 @@ add_library(neochat STATIC
     filetypesingleton.cpp
     login.cpp
     stickerevent.cpp
-    chatboxhelper.cpp
-    commandmodel.cpp
     webshortcutmodel.cpp
     blurhash.cpp
     blurhashimageprovider.cpp
@@ -40,6 +38,9 @@ add_library(neochat STATIC
     urlhelper.cpp
     windowcontroller.cpp
     linkpreviewer.cpp
+    completionmodel.cpp
+    completionproxymodel.cpp
+    actionsmodel.cpp
 )
 
 add_executable(neochat-app
@@ -84,7 +85,7 @@ else()
 endif()
 
 target_include_directories(neochat PRIVATE ${CMAKE_BINARY_DIR})
-target_link_libraries(neochat PUBLIC Qt::Core Qt::Quick Qt::Qml Qt::Gui Qt::Multimedia Qt::Network Qt::QuickControls2 KF5::I18n KF5::Kirigami2 KF5::Notifications KF5::ConfigCore KF5::ConfigGui KF5::CoreAddons Quotient cmark::cmark ${QTKEYCHAIN_LIBRARIES})
+target_link_libraries(neochat PUBLIC Qt::Core Qt::Quick Qt::Qml Qt::Gui Qt::Multimedia Qt::Network Qt::QuickControls2 KF5::I18n KF5::Kirigami2 KF5::Notifications KF5::ConfigCore KF5::ConfigGui KF5::CoreAddons KF5::SonnetCore Quotient cmark::cmark ${QTKEYCHAIN_LIBRARIES})
 if(TARGET QCoro5::Coro)
     target_link_libraries(neochat PUBLIC QCoro5::Coro)
 else()