Color and Style enhancements (#21784, #21799) (#21868)

Backport #21784
Backport #21799

These PRs provide tweaks and simplification to the less/css selectors, simplifying text color selectors and tweak arc-green colors with a follow-up to adjust the timeline 

See the original PRs for more details

templates/shared/issuelist.tmpl

@@ -160,7 +160,7 @@
 				</div>
 				<div class="issue-item-icon-right text grey">
 					{{if .NumComments}}
-						<a class="tdn" href="{{if .HTMLURL}}{{.HTMLURL}}{{else}}{{$.Link}}/{{.Index}}{{end}}">
+						<a class="tdn muted" href="{{if .HTMLURL}}{{.HTMLURL}}{{else}}{{$.Link}}/{{.Index}}{{end}}">
 							{{svg "octicon-comment" 16 "mr-2"}}{{.NumComments}}
 						</a>
 					{{end}}

templates/shared/user/authorlink.tmpl

@@ -1,3 +1 @@
-<a class="author"{{if gt .ID 0}} href="{{.HomeLink}}"{{end}}>
-	{{.GetDisplayName}}
-</a>
+<a class="author text black bold muted"{{if gt .ID 0}} href="{{.HomeLink}}"{{end}}>{{.GetDisplayName}}</a>

templates/shared/user/avatarlink.tmpl

@@ -1,3 +1 @@
-<a class="avatar"{{if gt .ID 0}} href="{{.HomeLink}}"{{end}}>
-	{{avatar .}}
-</a>
+<a class="avatar"{{if gt .ID 0}} href="{{.HomeLink}}"{{end}}>{{avatar .}}</a>

templates/shared/user/namelink.tmpl

@@ -1,3 +1 @@
-<a{{if gt .ID 0}} href="{{.HomeLink}}"{{end}}>
-	{{.GetDisplayName}}
-</a>
+<a{{if gt .ID 0}} href="{{.HomeLink}}"{{end}}>{{.GetDisplayName}}</a>