Create a cpp helper class to calculate the correct delegate width given it's parent width.
This is designed to be more robust and hopefully easier to understand than the current mass of javascript calcs.
BUG: 470167
This move the finding of links and the creation of a `linkpreviewer` into c++.
- The links are now extracted from the text in `texthandler`
- The `messageeventmodel` now creates and stores `linkpreviewers` for events that have links in the current room.
Two new model roles have been created to let a text delegate know when the link preview should be shown (`showLinkPreview`) and pass the link previewer (`linkPreviewer`). Empty link previewer are returned where link don't exist so the qml doesn't have to have checks for whether the parameters are undefined.
Improve the handling of text both when sending and receiving.
The main feature is to fix the linked bug (and a host of others that are unreported but similar) which is caused by the fact that we don't properly clean html. This mr does that as per the matrix spec https://spec.matrix.org/v1.5/client-server-api/#mroommessage-msgtypes. So any disallowed tags or attributes are removed and it does the special handling for certain attributes.
Additionally the functions are also designed to cover any other text formatting required, particularly fro received strings.
The receive side is covered by 2 functions `handleRecieveRichText` and `handleRecievePlainText`. The rich/plain in the function name refers to the output type not the input type (both can take plain and rich input), so `handleRecieveRichText` is called to get a string suitable to go in a rich text control and `handleRecievePlainText` for a plain control.
The functions also handle the following some of which was previously handled by `eventToString` in `NeoChatRoom`:
- Strip and reply from the string
- Format any user mentions
- Linkify links in plain strings
- Handle mxc urls in rich text (uses the new `room->makeMediaUrl` functionality from libQuotient)
- `handleRecievePlainText` also deals with markup making `NeoChatRoom->subtitle` redundant
There is also an extensive test suite which defines the behaviour and the best way to review this is probably to look at the tests and decide whether you agree with the expected output given the inputs and/or if there is any missing behaviour.
The final aim especially with the test suite is to give us a framework to make further updates in the future easier and hopefully prevent a new feature breaking old behaviour with the tests.
BUG: 463932 \
BUG: 466330 \
BUG: 466930
