Redo and fix trailing characters in user pills

This removes the handling of trailing chars from createMentionParts as we need to determine whether or not to insert the trailing char differently in different situations

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

src/editor/autocomplete.ts

@@ -125,10 +125,8 @@ export default class AutocompleteWrapperModel {
             case "at-room":
                 return [this.partCreator.atRoomPill(completionId), this.partCreator.plain(completion.suffix)];
             case "user":
-                // not using suffix here, because we also need to calculate
-                // the suffix when clicking a display name to insert a mention,
-                // which happens in createMentionParts
-                return this.partCreator.createMentionParts(this.partIndex, text, completionId);
+                // Insert suffix only if the pill is the part with index 0 - we are at the start of the composer
+                return this.partCreator.createMentionParts(this.partIndex === 0, text, completionId);
             case "command":
                 // command needs special handling for auto complete, but also renders as plain texts
                 return [(this.partCreator as CommandPartCreator).command(text)];