Fix right-aligned input icons (#30301)

Fix regression from #30194 where
right-aligned items would not display correctly.

Before and After:

<img width="285" alt="Screenshot 2024-04-06 at 01 12 11"
src="https://github.com/go-gitea/gitea/assets/115237/f9168db5-0f69-4b5d-ba17-b60145ac4a09">
<img width="285" alt="Screenshot 2024-04-06 at 01 11 49"
src="https://github.com/go-gitea/gitea/assets/115237/639ab6ed-d018-4e3a-9980-1f079e4ebe9d">

Frontpage search tweaked to accommodate (which was the reason for the
changes that broken above):

<img width="445" alt="Screenshot 2024-04-06 at 01 11 34"
src="https://github.com/go-gitea/gitea/assets/115237/1919220b-390e-463a-8e3d-33a3556bf111">
<img width="438" alt="Screenshot 2024-04-06 at 01 11 39"
src="https://github.com/go-gitea/gitea/assets/115237/fd94f8e4-1d56-4b04-99e3-1cd240bd7ab4">

web_src/css/modules/input.css

@@ -48,8 +48,11 @@
   cursor: default;
   position: absolute;
   text-align: center;
-  top: 50%;
-  transform: translateY(-50%);
+  top: 0;
+  right: 0;
+  margin: 0;
+  height: 100%;
+  width: 2.67142857em;
   opacity: 0.5;
   border-radius: 0 0.28571429rem 0.28571429rem 0;
   pointer-events: none;
@@ -58,6 +61,8 @@
 
 .ui.icon.input > i.icon.is-loading {
   position: absolute !important;
+  height: 28px;
+  top: 4px;
 }
 
 .ui.icon.input > i.icon.is-loading > * {
@@ -78,7 +83,7 @@
 
 .ui[class*="left icon"].input > i.icon {
   right: auto;
-  left: 8px;
+  left: 1px;
   border-radius: 0.28571429rem 0 0 0.28571429rem;
 }
 .ui[class*="left icon"].input > i.circular.icon {