Add oembed tags. Fix sharing and copy link button. Add text and file viewer

svelte/src/filesystem/viewers/File.svelte

@@ -0,0 +1,31 @@
+<script>
+import { createEventDispatcher } from "svelte";
+import IconBlock from "../../file_viewer/viewers/IconBlock.svelte";
+import { fs_thumbnail_url } from "../FilesystemUtil";
+let dispatch = createEventDispatcher()
+
+export let state
+</script>
+
+<h1>{state.base.name}</h1>
+
+<IconBlock icon_href={fs_thumbnail_url(state.root.id, state.base.path)}>
+	Type: {state.base.file_type}<br/>
+	No preview is available for this file type. Download to view it locally.
+	<br/>
+	<button class="button_highlight" on:click={() => {dispatch("download")}}>
+		<i class="icon">download</i>
+		<span>Download</span>
+	</button>
+</IconBlock>
+
+<style>
+h1 {
+	text-shadow: 1px 1px 3px var(--shadow_color);
+	line-break: anywhere;
+}
+.icon {
+	display: inline-block;
+	vertical-align: middle;
+}
+</style>