Merge pull request #4472 from matrix-org/t3chguy/complete_security_designs

Update login security copy and design to match Figma

src/components/views/elements/ButtonPlaceholder.js

@@ -1,19 +0,0 @@
-/*
-Copyright 2020 The Matrix.org Foundation C.I.C.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-export default function ButtonPlaceholder(props) {
-    return <div className="mx_ButtonPlaceholder">{props.children}</div>;
-}