PLT-6215 Major post list refactor (#6501)

* Major post list refactor

* Fix post and thread deletion

* Fix preferences not selecting correctly

* Fix military time displaying

* Fix UP key for editing posts

* Fix ESLint error

* Various fixes and updates per feedback

* Fix for permalink view

* Revert to old scrolling method and various fixes

* Add floating timestamp, new message indicator, scroll arrows

* Update post loading for focus mode and add visibility limit

* Fix pinning posts and a react warning

* Add loading UI updates from Asaad

* Fix refreshing loop

* Temporarily bump post visibility limit

* Update infinite scrolling

* Remove infinite scrolling

webapp/components/post_view/post_image.jsx

@@ -0,0 +1,100 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import React from 'react';
+import PropTypes from 'prop-types';
+
+export default class PostImageEmbed extends React.PureComponent {
+    static propTypes = {
+
+        /**
+         * The link to load the image from
+         */
+        link: PropTypes.string.isRequired,
+
+        /**
+         * Function to call when image is loaded
+         */
+        onLinkLoaded: PropTypes.func,
+
+        /**
+         * The function to call if image load fails
+         */
+        onLinkLoadError: PropTypes.func
+    }
+
+    constructor(props) {
+        super(props);
+
+        this.handleLoadComplete = this.handleLoadComplete.bind(this);
+        this.handleLoadError = this.handleLoadError.bind(this);
+
+        this.state = {
+            loaded: false,
+            errored: false
+        };
+    }
+
+    componentWillMount() {
+        this.loadImg(this.props.link);
+    }
+
+    componentWillReceiveProps(nextProps) {
+        if (nextProps.link !== this.props.link) {
+            this.setState({
+                loaded: false,
+                errored: false
+            });
+        }
+    }
+
+    componentDidUpdate(prevProps) {
+        if (!this.state.loaded && prevProps.link !== this.props.link) {
+            this.loadImg(this.props.link);
+        }
+    }
+
+    loadImg(src) {
+        const img = new Image();
+        img.onload = this.handleLoadComplete;
+        img.onerror = this.handleLoadError;
+        img.src = src;
+    }
+
+    handleLoadComplete() {
+        this.setState({
+            loaded: true,
+            errored: false
+        });
+        if (this.props.onLinkLoaded) {
+            this.props.onLinkLoaded();
+        }
+    }
+
+    handleLoadError() {
+        this.setState({
+            errored: true,
+            loaded: true
+        });
+        if (this.props.onLinkLoadError) {
+            this.props.onLinkLoadError();
+        }
+    }
+
+    render() {
+        if (this.state.errored || !this.state.loaded) {
+            return null;
+        }
+
+        return (
+            <div
+                className='post__embed-container'
+            >
+                <img
+                    className='img-div'
+                    src={this.props.link}
+                />
+            </div>
+        );
+    }
+}