feat: add tool to send a test notification (#16611)

Relates to https://github.com/coder/coder/issues/16463

Adds a CLI command, and API endpoint, to trigger a test notification for
administrators of a deployment.

coderd/notifications/testdata/rendered-templates/smtp/TemplateTestNotification.html.golden

@@ -0,0 +1,79 @@
+From: system@coder.com
+To: bobby@coder.com
+Subject: A test notification
+Message-Id: 02ee4935-73be-4fa1-a290-ff9999026b13@blush-whale-48
+Date: Fri, 11 Oct 2024 09:03:06 +0000
+Content-Type: multipart/alternative;  boundary=bbe61b741255b6098bb6b3c1f41b885773df633cb18d2a3002b68e4bc9c4
+MIME-Version: 1.0
+
+--bbe61b741255b6098bb6b3c1f41b885773df633cb18d2a3002b68e4bc9c4
+Content-Transfer-Encoding: quoted-printable
+Content-Type: text/plain; charset=UTF-8
+
+Hi Bobby,
+
+This is a test notification.
+
+
+View notification settings: http://test.com/deployment/notifications?tab=3D=
+settings
+
+--bbe61b741255b6098bb6b3c1f41b885773df633cb18d2a3002b68e4bc9c4
+Content-Transfer-Encoding: quoted-printable
+Content-Type: text/html; charset=UTF-8
+
+<!doctype html>
+<html lang=3D"en">
+  <head>
+    <meta charset=3D"UTF-8" />
+    <meta name=3D"viewport" content=3D"width=3Ddevice-width, initial-scale=
+=3D1.0" />
+    <title>A test notification</title>
+  </head>
+  <body style=3D"margin: 0; padding: 0; font-family: -apple-system, system-=
+ui, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarel=
+l', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif; color: #020617=
+; background: #f8fafc;">
+    <div style=3D"max-width: 600px; margin: 20px auto; padding: 60px; borde=
+r: 1px solid #e2e8f0; border-radius: 8px; background-color: #fff; text-alig=
+n: left; font-size: 14px; line-height: 1.5;">
+      <div style=3D"text-align: center;">
+        <img src=3D"https://coder.com/coder-logo-horizontal.png" alt=3D"Cod=
+er Logo" style=3D"height: 40px;" />
+      </div>
+      <h1 style=3D"text-align: center; font-size: 24px; font-weight: 400; m=
+argin: 8px 0 32px; line-height: 1.5;">
+        A test notification
+      </h1>
+      <div style=3D"line-height: 1.5;">
+        <p>Hi Bobby,</p>
+
+<p>This is a test notification.</p>
+      </div>
+      <div style=3D"text-align: center; margin-top: 32px;">
+       =20
+        <a href=3D"http://test.com/deployment/notifications?tab=3Dsettings"=
+ style=3D"display: inline-block; padding: 13px 24px; background-color: #020=
+617; color: #f8fafc; text-decoration: none; border-radius: 8px; margin: 0 4=
+px;">
+          View notification settings
+        </a>
+       =20
+      </div>
+      <div style=3D"border-top: 1px solid #e2e8f0; color: #475569; font-siz=
+e: 12px; margin-top: 64px; padding-top: 24px; line-height: 1.6;">
+        <p>&copy;&nbsp;2024&nbsp;Coder. All rights reserved&nbsp;-&nbsp;<a =
+href=3D"http://test.com" style=3D"color: #2563eb; text-decoration: none;">h=
+ttp://test.com</a></p>
+        <p><a href=3D"http://test.com/settings/notifications" style=3D"colo=
+r: #2563eb; text-decoration: none;">Click here to manage your notification =
+settings</a></p>
+        <p><a href=3D"http://test.com/settings/notifications?disabled=3Dc42=
+5f63e-716a-4bf4-ae24-78348f706c3f" style=3D"color: #2563eb; text-decoration=
+: none;">Stop receiving emails like this</a></p>
+      </div>
+    </div>
+  </body>
+</html>
+
+--bbe61b741255b6098bb6b3c1f41b885773df633cb18d2a3002b68e4bc9c4--

coderd/notifications/testdata/rendered-templates/webhook/TemplateTestNotification.json.golden

@@ -0,0 +1,25 @@
+{
+  "_version": "1.1",
+  "msg_id": "00000000-0000-0000-0000-000000000000",
+  "payload": {
+    "_version": "1.1",
+    "notification_name": "Test Notification",
+    "notification_template_id": "00000000-0000-0000-0000-000000000000",
+    "user_id": "00000000-0000-0000-0000-000000000000",
+    "user_email": "bobby@coder.com",
+    "user_name": "Bobby",
+    "user_username": "bobby",
+    "actions": [
+      {
+        "label": "View notification settings",
+        "url": "http://test.com/deployment/notifications?tab=settings"
+      }
+    ],
+    "labels": {},
+    "data": null
+  },
+  "title": "A test notification",
+  "title_markdown": "A test notification",
+  "body": "Hi Bobby,\n\nThis is a test notification.",
+  "body_markdown": "Hi Bobby,\n\nThis is a test notification."
+}