Add label/author/assignee filters to the user/org home issue list (#32779)

Replace #26661, fix #25979

Not perfect, but usable and much better than before. Since it is quite
complex, I am not quite sure whether there would be any regression, if
any, I will fix in first time.

I have tested the related pages many times: issue list, milestone issue
list, project view, user issue list, org issue list.

web_src/css/repo/list-header.css

@@ -5,13 +5,6 @@
   gap: .5rem;
 }
 
-.list-header-sort {
-  display: flex;
-  align-items: center;
-  padding-left: 1rem;
-  padding-right: 1rem;
-}
-
 .list-header-search {
   display: flex;
   flex: 1;
@@ -21,8 +14,22 @@
   min-width: 200px; /* to enable flexbox wrapping on mobile */
 }
 
-.list-header-search .input {
+.list-header-search > .ui.input {
   flex: 1;
+  min-width: 100px !important;
+}
+
+.list-header-search > .ui.input .ui.dropdown {
+  min-width: auto !important;
+}
+
+.list-header-filters {
+  display: flex;
+  align-items: center;
+}
+
+.list-header-filters > .item {
+  padding: 5px 0 5px 10px;
 }
 
 @media (max-width: 767.98px) {
@@ -32,8 +39,7 @@
   .list-header-toggle {
     order: 1;
   }
-  .list-header-sort {
+  .list-header-filters {
     order: 2;
-    margin-left: auto;
   }
 }