reactive button for checkboxes in table

ref #62

src/components/runners/RunnersOverview.svelte

@@ -61,7 +61,7 @@
         placeholder={$_('datatable.search')}
         aria-label={$_('datatable.search')}
         class="gridjs-input gridjs-search-input mb-4" />
-      <div class="block mb-1">
+      <div class="block mb-6">
         <label
           for="country"
           class="text-sm font-medium text-gray-700">{$_('filter-by-organization-team')}</label>
@@ -75,6 +75,18 @@
           items={selectgroups}
           isMulti={true} />
       </div>
+      <div class="h-12">
+        {#if current_runners.some((r) => r.is_selected === true)}
+          <button
+            on:click={() => {
+              //
+            }}
+            type="button"
+            class="w-full inline-flex justify-center rounded-md border border-transparent shadow-sm px-4 py-2 bg-gray-600 text-base font-medium text-white hover:bg-gray-700 focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-gray-500 sm:w-auto sm:text-sm">
+            generate sponsoring contracts
+          </button>
+        {/if}
+      </div>
       <div
         class="shadow border-b border-gray-200 sm:rounded-lg overflow-x-scroll">
         <table class="divide-y divide-gray-200 w-full">