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.

services/context/pagination.go

@@ -6,6 +6,7 @@ package context
 import (
 	"fmt"
 	"html/template"
+	"net/http"
 	"net/url"
 	"strings"
 
@@ -32,6 +33,18 @@ func (p *Pagination) AddParamString(key, value string) {
 	p.urlParams = append(p.urlParams, urlParam)
 }
 
+func (p *Pagination) AddParamFromRequest(req *http.Request) {
+	for key, values := range req.URL.Query() {
+		if key == "page" || len(values) == 0 {
+			continue
+		}
+		for _, value := range values {
+			urlParam := fmt.Sprintf("%s=%v", key, url.QueryEscape(value))
+			p.urlParams = append(p.urlParams, urlParam)
+		}
+	}
+}
+
 // GetParams returns the configured URL params
 func (p *Pagination) GetParams() template.URL {
 	return template.URL(strings.Join(p.urlParams, "&"))