feat: redesign project sharing & initial registration

redesigned the project sharing popup to be a multi select dropdown
that populates the options by using the input as a fuzzy search filter
on the current users & invited users.

users can now also be directly invited by email from the project share
window. if invited this way, then the user will receive an email
that sends them to a registration page, then a confirmation page.

the initial registration was always redone so that it uses a similar
system to the above in that it now will accept the first registered
user if there are no other accounts (besides 'system').

frontend/src/shared/icons/DotCircle.tsx

@@ -0,0 +1,12 @@
+import React from 'react';
+import Icon, { IconProps } from './Icon';
+
+const DotCircle: React.FC<IconProps> = ({ width = '16px', height = '16px', className }) => {
+  return (
+    <Icon width={width} height={height} className={className} viewBox="0 0 512 512">
+      <path d="M256 8C119.033 8 8 119.033 8 256s111.033 248 248 248 248-111.033 248-248S392.967 8 256 8zm80 248c0 44.112-35.888 80-80 80s-80-35.888-80-80 35.888-80 80-80 80 35.888 80 80z" />
+    </Icon>
+  );
+};
+
+export default DotCircle;