Timeline and color tweaks (#21799)

Followup to https://github.com/go-gitea/gitea/pull/21784.

- Restore muted effect on timeline author and issuelist comment icon
- Remove whitespace inside shared user templates, fixing link hover
underline
- Use shared author link template more
- Use `bold` class instead of CSS
- Fix grey-light color being too dark on arc-green
- Add missing black-light color
- Fix issuelist progress bar color
- Fix various other cases of missing `.muted`

<img width="416" alt="Screenshot 2022-11-13 at 12 15 22"
src="https://user-images.githubusercontent.com/115237/201519497-1d4725c6-bc8b-47b5-9f68-1278ac9a8c92.png">
<img width="324" alt="Screenshot 2022-11-13 at 12 16 52"
src="https://user-images.githubusercontent.com/115237/201519501-c0d03700-f9af-4316-ab46-482f2c7c738b.png">
<img width="79" alt="Screenshot 2022-11-13 at 12 30 55"
src="https://user-images.githubusercontent.com/115237/201519502-46dc2d73-bbdf-4a2e-84d3-d2976f793163.png">
<img width="440" alt="Screenshot 2022-11-13 at 12 41 03"
src="https://user-images.githubusercontent.com/115237/201519876-ada33948-f84a-4aeb-a40d-5c873f9a49e9.png">
<img width="213" alt="Screenshot 2022-11-13 at 12 52 54"
src="https://user-images.githubusercontent.com/115237/201520291-a4d7238e-aeca-46c7-9008-8b644b1b676e.png">
<img width="208" alt="Screenshot 2022-11-13 at 12 56 16"
src="https://user-images.githubusercontent.com/115237/201520436-aa8ba109-b959-42fb-831a-021e806c7082.png">

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/less/_repository.less

@@ -829,7 +829,7 @@
 
         .timeline-avatar {
           position: absolute;
-          left: -72px;
+          left: -68px;
 
           img {
             width: 40px !important;
@@ -846,7 +846,6 @@
         .avatar img {
           width: 20px;
           height: 20px;
-          margin: 0 .25rem;
           vertical-align: middle;
         }
 
@@ -981,10 +980,6 @@
           margin-top: 4px;
         }
 
-        .author {
-          font-weight: 600;
-        }
-
         .comment-form-reply .footer {
           padding-bottom: 1em;
         }
@@ -1165,9 +1160,12 @@
         padding-left: 15px;
 
         .detail {
-          font-size: .9rem;
-          margin-top: 5px;
-          margin-left: 8px;
+          margin-top: 4px;
+          margin-left: 14px;
+
+          .svg {
+            margin-right: 2px;
+          }
         }
 
         .segments {
@@ -2723,12 +2721,10 @@
 
   a {
     color: var(--color-text);
-    text-decoration: none;
   }
 
   a:hover {
     color: var(--color-primary);
-    text-decoration: none;
   }
 }