luci-app-commands: rewrite to client side rendering

Rewrite the luci-app-command configuration to client side cbi forms and
port the server side templates and controller logic to ucode.

Also utilize a query string parameter to pass custom arguments.

Fixes: #5559
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

applications/luci-app-commands/ucode/template/commands_public.ut

@@ -0,0 +1,48 @@
+{#
+ Copyright 2016 t123yh <t123yh@outlook.com>
+ Copyright 2022 Jo-Philipp Wich <jo@mein.io>
+ Licensed to the public under the Apache License 2.0.
+-#}
+
+{%
+    include('header', { blank_page: true, css: `
+        .alert-success {
+            color: #3c763d;
+            background-color: #dff0d8;
+            border-color: #d6e9c6;
+        }
+
+        .alert {
+            padding: 15px;
+            margin-bottom: 20px;
+            border: 1px solid transparent;
+            border-radius: 4px;
+        }
+
+        .alert-warning {
+            color: #8a6d3b;
+            background-color: #fcf8e3;
+            border-color: #faebcc;
+        }
+    ` });
+-%}
+
+<div class="alert alert-success" role="alert">
+    {% if (exitcode == 0): %}
+        {{ _('Command executed successfully.') }}
+    {% else %}
+        {{ sprintf(_('Command exited with status code %d'), exitcode) }}
+    {% endif %}
+</div>
+
+{% if (length(stdout)): %}
+    <h3>{{ _('Standard Output') }}</h3>
+    <pre>{{ entityencode(stdout) }}</pre>
+{% endif %}
+
+{% if (length(stderr)): %}
+    <h3>{{ _('Standard Error') }}</h3>
+    <pre>{{ entityencode(stderr) }}</pre>
+{% endif %}
+
+{% include('footer', { blank_page: true }) %}