Add a fact checker feature with updated styling (#835)

- Add an experimental feature used for fact-checking falsifiable statements with customizable models. See attached screenshot for example. Once you input a statement that needs to be fact-checked, Khoj goes on a research spree to verify or refute it.
- Integrate frontend libraries for [Tailwind](https://tailwindcss.com/) and [ShadCN](https://ui.shadcn.com/) for easier UI development. Update corresponding styling for some existing UI components. 
- Add component for model selection 
- Add backend support for sharing arbitrary packets of data that will be consumed by specific front-end views in shareable scenarios

src/interface/web/app/components/shareLink/shareLink.tsx

@@ -0,0 +1,63 @@
+import {
+    Dialog,
+    DialogContent,
+    DialogDescription,
+    DialogHeader,
+    DialogTitle,
+    DialogTrigger,
+} from "@/components/ui/dialog";
+
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+
+interface ShareLinkProps {
+    buttonTitle: string;
+    title: string;
+    description: string;
+    url: string;
+    onShare: () => void;
+}
+
+function copyToClipboard(text: string) {
+    const clipboard = navigator.clipboard;
+    if (!clipboard) {
+        return;
+    }
+    clipboard.writeText(text);
+}
+
+export default function ShareLink(props: ShareLinkProps) {
+    return (
+        <Dialog>
+            <DialogTrigger
+                className="inline-flex items-center justify-center whitespace-nowrap rounded-md text-sm font-medium ring-offset-background transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:pointer-events-none disabled:opacity-50 bg-primary text-primary-foreground hover:bg-primary/90 h-10 px-4 py-2"
+                onClick={props.onShare}>
+                    {props.buttonTitle}
+            </DialogTrigger>
+            <DialogContent>
+                <DialogHeader>
+                <DialogTitle>{props.title}</DialogTitle>
+                <DialogDescription>
+                    {props.description}
+                </DialogDescription>
+                </DialogHeader>
+            <div className="flex items-center space-x-2">
+                <div className="grid flex-1 gap-2">
+                    <Label htmlFor="link" className="sr-only">
+                    Link
+                    </Label>
+                    <Input
+                    id="link"
+                    defaultValue={props.url}
+                    readOnly
+                    />
+                </div>
+                <Button type="submit" size="sm" className="px-3" onClick={() => copyToClipboard(props.url)}>
+                    <span>Copy</span>
+                </Button>
+            </div>
+            </DialogContent>
+        </Dialog>
+    );
+}