Manage Pledge: Add shortcode to email link for updating.

See #5

plugins/wporg-5ftf/views/form-pledge-request-manage-link.php

@@ -0,0 +1,74 @@
+<?php
+
+namespace WordPressDotOrg\FiveForTheFuture\View;
+
+defined( 'WPINC' ) || die();
+
+/**
+ * @var array $errors
+ */
+
+// Hide it if it hasn't submitted, but show success/error messages if it was submitted.
+$hidden = empty( $errors ) && empty( $_POST['get_manage_pledge_link'] ) ? 'hidden' : '';
+
+?>
+
+<button id="toggle-management-link-form">
+	<span class="dashicons dashicons-edit"></span>
+	<?php esc_html_e( 'Edit Pledge', 'wporg-5ftf' ); ?>
+</button>
+
+<div id="request-management-link" <?php echo esc_attr( $hidden ); ?> >
+	<p>
+		<?php esc_html_e( 'Only pledge admins can edit pledges.', 'wporg-5ftf' ); ?>
+	</p>
+
+	<p>
+		<?php esc_html_e( "If you're the admin, enter your email address and a confirmation link will be sent to you.", 'wporg-5ftf' ); ?>
+	</p>
+
+	<form action="#form-messages" method="post">
+		<input type="hidden" name="pledge_id" value="<?php echo esc_attr( get_post()->ID ); ?>" />
+
+		<label for="pledge_admin_address">
+			<?php esc_html_e( 'Email Address', 'wporg-5ftf' ); ?>
+		</label>
+
+		<input
+			id="pledge_admin_address"
+			name="pledge_admin_address"
+			type="email"
+			required
+			value=""
+		/>
+
+		<input
+			type="submit"
+			name="get_manage_pledge_link"
+			value="Submit"
+		/>
+
+		<?php require __DIR__ . '/partial-result-messages.php'; ?>
+	</form>
+</div>
+
+<script>
+	( function() {
+		var toggleLinkFormButton = document.getElementById( 'toggle-management-link-form' ),
+			linkForm = document.getElementById( 'request-management-link' );
+
+		// Toggle the form when the button is clicked.
+		toggleLinkFormButton.addEventListener( 'click', function() {
+			switch( linkForm.hidden ) {
+				case true:
+					linkForm.hidden = false;
+					linkForm.scrollIntoView( { behavior: 'smooth' } );
+					break;
+
+				default:
+					linkForm.hidden = true;
+					break;
+			}
+		} );
+	}() );
+</script>