This makes sure the selection state is correct when moving the cursor through an entity in the composer but only in rich text mode. https://github.com/vector-im/riot-web/issues/4666 still persists despite this, probably because the text content inserted during a completion in markdown mode has a different length to the text node within the entity.
fixesvector-im/riot-web#4654
Instead of relying on the local avatar/displayname of a user, request the data from the server and update the pill if it shows up.
This required a slight refactor which means we're not doing everything in `render` now. Also I noticed unknown rooms weren't being rendered _at all_! So now you get something that looks like a normal link but with the room alias/ID in it.
Instead of blindly stripping all MD mentions, only strip those that were tab-completed. We do this by adding the `isCompleted` flag to the Entity data.
This isn't an entirely side-effect-free refactoring:
- the text of the timeline pills is now either the room ID/alias or user ID/ display name of the linked resource (which means that until we do a roundtrip to get user displaynames, mentions for users not in the current room will have their user IDs shown instead of what was in the link body).
- timeline links to rooms without avatars are now rendered as links
- fixed issue that would throw an error whilst rendering (i.e. unusable client) a room link to a room that the client doesn't know about
These will appear decorated because they are inserted as entities. It was necessary to modify pills to have an explicit linkText that is derived from the `href` being pillified (and is thus no longer the inserted completion but rather the display name (or user ID) or room alias.
by inspecting whether multiple lines are selected or the selection is empty. If either of these are true, insert a code block surrounding the selection, otherwise insert single backticks around the selection for inline code formatting.
the js-sdk is making some of its APIs asynchronous, and adding an `initCrypto`
method which you have to call.
Particular methods we need to worry about are:
* `getStoredDevice`
* `getStoredDevicesForUser`
* `getEventSenderDeviceInfo`
* `isEventSenderVerified`
