Move some functions from issue.go to standalone files (#32468)

Just functions move, no code change.

---------

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

routers/web/repo/issue_poster.go

@@ -0,0 +1,66 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"net/http"
+	"slices"
+	"strings"
+
+	repo_model "code.gitea.io/gitea/models/repo"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/setting"
+	shared_user "code.gitea.io/gitea/routers/web/shared/user"
+	"code.gitea.io/gitea/services/context"
+)
+
+type userSearchInfo struct {
+	UserID     int64  `json:"user_id"`
+	UserName   string `json:"username"`
+	AvatarLink string `json:"avatar_link"`
+	FullName   string `json:"full_name"`
+}
+
+type userSearchResponse struct {
+	Results []*userSearchInfo `json:"results"`
+}
+
+// IssuePosters get posters for current repo's issues/pull requests
+func IssuePosters(ctx *context.Context) {
+	issuePosters(ctx, false)
+}
+
+func PullPosters(ctx *context.Context) {
+	issuePosters(ctx, true)
+}
+
+func issuePosters(ctx *context.Context, isPullList bool) {
+	repo := ctx.Repo.Repository
+	search := strings.TrimSpace(ctx.FormString("q"))
+	posters, err := repo_model.GetIssuePostersWithSearch(ctx, repo, isPullList, search, setting.UI.DefaultShowFullName)
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, err)
+		return
+	}
+
+	if search == "" && ctx.Doer != nil {
+		// the returned posters slice only contains limited number of users,
+		// to make the current user (doer) can quickly filter their own issues, always add doer to the posters slice
+		if !slices.ContainsFunc(posters, func(user *user_model.User) bool { return user.ID == ctx.Doer.ID }) {
+			posters = append(posters, ctx.Doer)
+		}
+	}
+
+	posters = shared_user.MakeSelfOnTop(ctx.Doer, posters)
+
+	resp := &userSearchResponse{}
+	resp.Results = make([]*userSearchInfo, len(posters))
+	for i, user := range posters {
+		resp.Results[i] = &userSearchInfo{UserID: user.ID, UserName: user.Name, AvatarLink: user.AvatarLink(ctx)}
+		if setting.UI.DefaultShowFullName {
+			resp.Results[i].FullName = user.FullName
+		}
+	}
+	ctx.JSON(http.StatusOK, resp)
+}