Rework delete org and rename org UI (#34762)

# What's the problem of the original implementation

Renaming organization will mix with organization's information change
make the operation difficult to keep consistent.

This PR created a danger zone like what's repository setting. It also
moved organization's `rename` and `delete` operations to this zone. The
original updating repository will not change the name any more.

This is also a step to extract the `updaterepository` function
completely.

Before:


![image](https://github.com/user-attachments/assets/d097dfdf-07be-4d79-8fcf-e78822515575)

![image](https://github.com/user-attachments/assets/42ee832c-cb44-41ec-9fe3-92a1c94747d2)

After:


![image](https://github.com/user-attachments/assets/f7700ed7-f104-4302-a924-09e118f24be3)

![image](https://github.com/user-attachments/assets/4c49952a-578e-4d14-bd01-4a68c9e02412)

![image](https://github.com/user-attachments/assets/814829d3-00fe-4e87-ae05-625c129170d2)

![image](https://github.com/user-attachments/assets/b067b263-c909-4b48-b23c-73481c32d350)

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/css/base.css

@@ -30,6 +30,10 @@
   --page-spacing: 16px; /* space between page elements */
   --page-margin-x: 32px; /* minimum space on left and right side of page */
   --page-space-bottom: 64px; /* space between last page element and footer */
+
+  /* z-index */
+  --z-index-modal: 1001; /* modal dialog, hard-coded from Fomantic modal.css */
+  --z-index-toast: 1002; /* should be larger than modal */
 }
 
 @media (min-width: 768px) and (max-width: 1200px) {

web_src/css/modules/dimmer.css

@@ -20,7 +20,7 @@
   opacity: 1;
 }
 
-.ui.dimmer > * {
+.ui.dimmer > .ui.modal {
   position: static;
   margin-top: auto !important;
   margin-bottom: auto !important;

web_src/css/modules/toast.css

@@ -3,7 +3,7 @@
   position: fixed;
   opacity: 0;
   transition: all .2s ease;
-  z-index: 500;
+  z-index: var(--z-index-toast);
   border-radius: var(--border-radius);
   box-shadow: 0 8px 24px var(--color-shadow);
   display: flex;