website/docs: Flesh out Google Workspaces SAML. (#12701)

* website/docs: Google Workspaces SAML.

- Moves Google Cloud doc page to sibling article.
- Adds Index page for Google sources
- Adds Index page for federated sources

* website/docs: Re-order tags.

website/src/css/custom.css

@@ -1,3 +1,5 @@
+/*#region root*/
+
 :root {
     --ifm-color-primary: #fd4b2d;
     --ifm-color-primary-dark: #fd320f;
@@ -11,6 +13,10 @@
     --ifm-navbar-link-hover-color: var(--ifm-color-gray-1000);
 }
 
+/*#endregion*/
+
+/*#region Buttons*/
+
 .button.button--outline {
     color: var(--white) !important;
     --ifm-button-border-color: var(--white) !important;
@@ -21,6 +27,10 @@
     --ifm-button-background-color: var(--white);
 }
 
+/*#endregion*/
+
+/*#region Navbar*/
+
 .navbar {
     background-color: var(--ifm-color-primary);
     box-shadow: none;
@@ -37,6 +47,10 @@
     stroke: var(--white);
 }
 
+/*#endregion*/
+
+/*#region Header*/
+
 .header-github-link:hover {
     opacity: 0.6;
 }
@@ -63,6 +77,8 @@
         no-repeat;
 }
 
+/*#endregion*/
+
 @media (min-width: 1600px) {
     #__docusaurus_skipToContent_fallback > div {
         align-self: center;
@@ -133,3 +149,25 @@ body {
     font-size: 0.75rem;
     vertical-align: middle;
 }
+
+/*#endregion*/
+
+/*#region Mermaid*/
+
+.docusaurus-mermaid-container {
+    /* Improve contrast. */
+    & .messageText {
+        stroke: var(--ifm-background-color) !important;
+        stroke-width: 10;
+        fill: var(--ifm-color-content) !important;
+        paint-order: stroke;
+    }
+}
+/*#endregion*/
+
+.markdown {
+    /* Remove empty table headers. */
+    & table > thead:has(> tr > th:empty):not(:has(> tr > th:not(:empty))) {
+        display: none;
+    }
+}