Remove svg.svg class, restore .rss-icon (#24667)

Fix regression from #24476 where
the `svg.svg` class misaligns SVG icons across the site and streched
buttons unintentionally in vertical height.

Before (button 30.3px):
<img width="157" alt="Screenshot 2023-05-11 at 22 09 42"
src="https://github.com/go-gitea/gitea/assets/115237/0fd137ab-ab52-4cf8-afca-c45776d526d0">

After (button 30px):
<img width="160" alt="Screenshot 2023-05-11 at 22 09 59"
src="https://github.com/go-gitea/gitea/assets/115237/4b741f4b-0fd2-4fae-9bee-16a7deb098e8">

[vertical-align:
middle](https://developer.mozilla.org/en-US/docs/Web/CSS/vertical-align)
is not suitable to align icons to text because

> Aligns the middle of the element with the baseline plus half the
x-height of the parent.

Example of `vertical-align: middle` from MDN:

<img width="232" alt="Screenshot 2023-05-11 at 22 29 28"
src="https://github.com/go-gitea/gitea/assets/115237/179fb756-85a1-4cab-8219-1a4958f333e2">

So I think the
[existing](https://github.com/go-gitea/gitea/blob/365bb77a5497d492836bf823cf780c823db27e8c/web_src/css/svg.css#L3)
`vertical-align: text-top` is generally still the best bet:

<img width="241" alt="Screenshot 2023-05-11 at 22 34 24"
src="https://github.com/go-gitea/gitea/assets/115237/0cd6edf5-12c0-4bdb-8771-a900f5ba2d35">

Co-authored-by: Giteabot <teabot@gitea.io>

Author: silverwind

templates/org/home.tmpl

@@ -10,7 +10,7 @@
 					{{if .Org.Visibility.IsPrivate}}<span class="ui large basic horizontal label">{{.locale.Tr "org.settings.visibility.private_shortname"}}</span>{{end}}
 				</span>
 				{{if .EnableFeed}}
-					<a class="muted" href="{{.Org.HomeLink}}.rss" data-tooltip-content="{{.locale.Tr "rss_feed"}}">{{svg "octicon-rss" 24}}</a>
+					<a class="rss-icon gt-mx-3" href="{{.Org.HomeLink}}.rss" data-tooltip-content="{{.locale.Tr "rss_feed"}}">{{svg "octicon-rss" 24}}</a>
 				{{end}}
 			</div>
 			{{if $.RenderedDescription}}<div class="render-content markup">{{$.RenderedDescription|Str2html}}</div>{{end}}

templates/repo/header.tmpl

@@ -36,7 +36,7 @@
 						{{end}}
 					</div>
 					{{if $.EnableFeed}}
-						<a class="muted gt-ml-3" href="{{$.RepoLink}}.rss" data-tooltip-content="{{$.locale.Tr "rss_feed"}}">{{svg "octicon-rss" 18}}</a>
+						<a class="rss-icon gt-ml-3" href="{{$.RepoLink}}.rss" data-tooltip-content="{{$.locale.Tr "rss_feed"}}">{{svg "octicon-rss" 18}}</a>
 					{{end}}
 				</div>
 				{{if $.IsPullMirror}}

templates/repo/release_tag_header.tmpl

@@ -11,7 +11,7 @@
 				{{end}}
 			</h2>
 			{{if .EnableFeed}}
-				<a class="muted gt-mx-3" href="{{.RepoLink}}/{{if .PageIsTagList}}tags{{else}}releases{{end}}.rss" data-tooltip-content="{{.locale.Tr "rss_feed"}}">{{svg "octicon-rss" 18}}</a>
+				<a class="rss-icon gt-mx-3" href="{{.RepoLink}}/{{if .PageIsTagList}}tags{{else}}releases{{end}}.rss" data-tooltip-content="{{.locale.Tr "rss_feed"}}">{{svg "octicon-rss" 18}}</a>
 			{{end}}
 		</div>
 		{{if and (not .PageIsTagList) .CanCreateRelease}}

web_src/css/base.css

@@ -364,12 +364,6 @@ a.label,
   text-decoration: none !important;
 }
 
-/* for most cases, we only use our svg icon as inline icon, so we need to make them inline-block and vertical-align: middle */
-svg.svg {
-  display: inline-block;
-  vertical-align: middle;
-}
-
 .ui.red.labels .label,
 .ui.ui.ui.red.label,
 .ui.red.button,
@@ -2595,6 +2589,11 @@ a.ui.basic.label:hover {
   line-height: .67em;
 }
 
+.rss-icon {
+  display: inline-flex;
+  color: var(--color-text-light-1);
+}
+
 table th[data-sortt-asc]:hover,
 table th[data-sortt-desc]:hover {
   background: rgba(0, 0, 0, 0.1) !important;

web_src/js/components/RepoBranchTagSelector.vue

@@ -39,7 +39,7 @@
       <div class="scrolling menu" ref="scrollContainer">
         <div v-for="(item, index) in filteredItems" :key="item.name" class="item" :class="{selected: item.selected, active: active === index}" @click="selectItem(item)" :ref="'listItem' + index">
           {{ item.name }}
-          <a v-if="enableFeed && mode === 'branches'" role="button" class="ui compact right muted" :href="rssURLPrefix + item.url" target="_blank" @click.stop>
+          <a v-if="enableFeed && mode === 'branches'" role="button" class="rss-icon ui compact right" :href="rssURLPrefix + item.url" target="_blank" @click.stop>
             <svg-icon name="octicon-rss" :size="14"/>
           </a>
         </div>