DRY matrix.to link generation so it is all changeable in one class

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/autocomplete/UserProvider.js

@@ -28,6 +28,7 @@ import _sortBy from 'lodash/sortBy';
 import MatrixClientPeg from '../MatrixClientPeg';
 
 import type {Room, RoomMember} from 'matrix-js-sdk';
+import {makeUserPermalink} from "../matrix-to";
 
 const USER_REGEX = /@\S*/g;
 
@@ -104,7 +105,7 @@ export default class UserProvider extends AutocompleteProvider {
                     // relies on the length of the entity === length of the text in the decoration.
                     completion: user.rawDisplayName.replace(' (IRC)', ''),
                     suffix: range.start === 0 ? ': ' : ' ',
-                    href: 'https://matrix.to/#/' + user.userId,
+                    href: makeUserPermalink(user.userId),
                     component: (
                         <PillCompletion
                             initialComponent={<MemberAvatar member={user} width={24} height={24} />}