Optimize the styling of icon buttons within file-header-right (#32675)

Optimize partial layout and styling to achieve uniformity and
consistency.

Some buttons's structure is `<a><span><svg/></span></a>`, while others
buttons's structure is `<a><svg/></a>`. Additionally, some buttons have
icons that are **14** in size, while others have icons that are **16**.
Now, the layout has been unified to structure `<a><svg/></a>`, and the
icon size for all buttons has been standardized to the default size of
**16**.

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

templates/repo/view_file.tmpl

@@ -56,21 +56,21 @@
 						<button class="ui mini basic button escape-button">{{ctx.Locale.Tr "repo.escape_control_characters"}}</button>
 					{{end}}
 				</div>
-				<a download href="{{$.RawFileLink}}"><span class="btn-octicon" data-tooltip-content="{{ctx.Locale.Tr "repo.download_file"}}">{{svg "octicon-download"}}</span></a>
-				<a id="copy-content" class="btn-octicon {{if not .CanCopyContent}} disabled{{end}}"{{if or .IsImageFile (and .HasSourceRenderedToggle (not .IsDisplayingSource))}} data-link="{{$.RawFileLink}}"{{end}} data-tooltip-content="{{if .CanCopyContent}}{{ctx.Locale.Tr "copy_content"}}{{else}}{{ctx.Locale.Tr "copy_type_unsupported"}}{{end}}">{{svg "octicon-copy" 14}}</a>
+				<a download class="btn-octicon" data-tooltip-content="{{ctx.Locale.Tr "repo.download_file"}}" href="{{$.RawFileLink}}">{{svg "octicon-download"}}</a>
+				<a id="copy-content" class="btn-octicon {{if not .CanCopyContent}} disabled{{end}}"{{if or .IsImageFile (and .HasSourceRenderedToggle (not .IsDisplayingSource))}} data-link="{{$.RawFileLink}}"{{end}} data-tooltip-content="{{if .CanCopyContent}}{{ctx.Locale.Tr "copy_content"}}{{else}}{{ctx.Locale.Tr "copy_type_unsupported"}}{{end}}">{{svg "octicon-copy"}}</a>
 				{{if .EnableFeed}}
 				<a class="btn-octicon" href="{{$.FeedURL}}/rss/{{$.BranchNameSubURL}}/{{PathEscapeSegments .TreePath}}" data-tooltip-content="{{ctx.Locale.Tr "rss_feed"}}">
-					{{svg "octicon-rss" 14}}
+					{{svg "octicon-rss"}}
 				</a>
 				{{end}}
 				{{if .Repository.CanEnableEditor}}
 					{{if .CanEditFile}}
-						<a href="{{.RepoLink}}/_edit/{{PathEscapeSegments .BranchName}}/{{PathEscapeSegments .TreePath}}"><span class="btn-octicon" data-tooltip-content="{{.EditFileTooltip}}">{{svg "octicon-pencil"}}</span></a>
+						<a class="btn-octicon" data-tooltip-content="{{.EditFileTooltip}}" href="{{.RepoLink}}/_edit/{{PathEscapeSegments .BranchName}}/{{PathEscapeSegments .TreePath}}">{{svg "octicon-pencil"}}</a>
 					{{else}}
 						<span class="btn-octicon disabled" data-tooltip-content="{{.EditFileTooltip}}">{{svg "octicon-pencil"}}</span>
 					{{end}}
 					{{if .CanDeleteFile}}
-						<a href="{{.RepoLink}}/_delete/{{PathEscapeSegments .BranchName}}/{{PathEscapeSegments .TreePath}}"><span class="btn-octicon btn-octicon-danger"  data-tooltip-content="{{.DeleteFileTooltip}}">{{svg "octicon-trash"}}</span></a>
+						<a class="btn-octicon btn-octicon-danger" data-tooltip-content="{{.DeleteFileTooltip}}" href="{{.RepoLink}}/_delete/{{PathEscapeSegments .BranchName}}/{{PathEscapeSegments .TreePath}}">{{svg "octicon-trash"}}</a>
 					{{else}}
 						<span class="btn-octicon disabled" data-tooltip-content="{{.DeleteFileTooltip}}">{{svg "octicon-trash"}}</span>
 					{{end}}