feat(issue-search): support query syntax (#9109)

List of currently supported filters:

- `is:open` (or `-is:closed`)
- `is:closed` (or `-is:open`)
- `is:all`
- `author:<username>`
- `assignee:<username>`
- `review:<username>`
- `mentions:<username>`
- `modified:[>|<]<date>`, where `<date>` is the last update date.
- `sort:<by>:[asc|desc]`, where `<by>` is among
	- created
	- comments
	- updated
	- deadline

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/9109
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Reviewed-by: Ellen Εμιλία Άννα Zscheile <fogti@noreply.codeberg.org>
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Shiny Nematoda <snematoda.751k2@aleeas.com>
Co-committed-by: Shiny Nematoda <snematoda.751k2@aleeas.com>

modules/util/string.go

@@ -3,7 +3,11 @@
 
 package util
 
-import "unsafe"
+import (
+	"slices"
+	"strings"
+	"unsafe"
+)
 
 func isSnakeCaseUpper(c byte) bool {
 	return 'A' <= c && c <= 'Z'
@@ -117,3 +121,37 @@ func ASCIILower(b byte) byte {
 	}
 	return b
 }
+
+func RemoveAllStr(s string, prefix bool, all ...string) string {
+	if len(s) == 0 {
+		return ""
+	}
+
+	sb, first := strings.Builder{}, true
+	for field := range strings.FieldsSeq(s) {
+		if hasAny(field, prefix, all...) {
+			continue
+		}
+		if first {
+			first = false
+			goto write
+		}
+		sb.WriteRune(' ')
+	write:
+		sb.WriteString(field)
+	}
+	return sb.String()
+}
+
+func hasAny(s string, prefix bool, all ...string) bool {
+	if !prefix {
+		return slices.Contains(all, s)
+	}
+
+	for _, field := range all {
+		if strings.HasPrefix(s, field) {
+			return true
+		}
+	}
+	return false
+}