feat: create new header component

This component is now required for forms.

src/components/header.rs

@@ -0,0 +1,40 @@
+use leptos::prelude::*;
+
+/// # Header Component
+/// 
+/// A simple header that may also contain a description. Should be used to annotate sections and
+/// forms, with extra information about how that section/form will work.
+/// 
+/// Example usage:
+/// ```
+/// view! {
+///     <Header
+///         title: "Example header"
+///         description: "Example description"
+///     />
+/// }
+/// ```
+#[component]
+pub fn Header(
+    /// The title of the header. Must always be present.
+    #[prop(into)] title: Signal<String>,
+    /// The description of the header. Hidden when nothing i s
+    #[prop(optional, into)] description: Signal<String>,
+) -> impl IntoView {
+    let show_description = Signal::derive(move || {
+        !description.get().is_empty()
+    });
+    
+    view! {
+        <div class="m-1.5 mb-5">
+            <div class="text-3xl font-bold">
+                {title}
+            </div>
+            <Show when=move || show_description.get()>
+                <div>
+                    {description}
+                </div>
+            </Show>
+        </div>
+    }
+}