Move some files under repo/setting (#25585)

There are too many files under `routers/web/repo` and the file
`routers/web/repo/setting.go` is too big.
This PR move all setting related routers' body functions under
`routers/web/repo/setting` and also split `routers/web/repo/setting.go`

routers/web/repo/setting/avatar.go

@@ -0,0 +1,76 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"errors"
+	"fmt"
+	"io"
+
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/typesniffer"
+	"code.gitea.io/gitea/modules/web"
+	"code.gitea.io/gitea/services/forms"
+	repo_service "code.gitea.io/gitea/services/repository"
+)
+
+// UpdateAvatarSetting update repo's avatar
+func UpdateAvatarSetting(ctx *context.Context, form forms.AvatarForm) error {
+	ctxRepo := ctx.Repo.Repository
+
+	if form.Avatar == nil {
+		// No avatar is uploaded and we not removing it here.
+		// No random avatar generated here.
+		// Just exit, no action.
+		if ctxRepo.CustomAvatarRelativePath() == "" {
+			log.Trace("No avatar was uploaded for repo: %d. Default icon will appear instead.", ctxRepo.ID)
+		}
+		return nil
+	}
+
+	r, err := form.Avatar.Open()
+	if err != nil {
+		return fmt.Errorf("Avatar.Open: %w", err)
+	}
+	defer r.Close()
+
+	if form.Avatar.Size > setting.Avatar.MaxFileSize {
+		return errors.New(ctx.Tr("settings.uploaded_avatar_is_too_big"))
+	}
+
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return fmt.Errorf("io.ReadAll: %w", err)
+	}
+	st := typesniffer.DetectContentType(data)
+	if !(st.IsImage() && !st.IsSvgImage()) {
+		return errors.New(ctx.Tr("settings.uploaded_avatar_not_a_image"))
+	}
+	if err = repo_service.UploadAvatar(ctx, ctxRepo, data); err != nil {
+		return fmt.Errorf("UploadAvatar: %w", err)
+	}
+	return nil
+}
+
+// SettingsAvatar save new POSTed repository avatar
+func SettingsAvatar(ctx *context.Context) {
+	form := web.GetForm(ctx).(*forms.AvatarForm)
+	form.Source = forms.AvatarLocal
+	if err := UpdateAvatarSetting(ctx, *form); err != nil {
+		ctx.Flash.Error(err.Error())
+	} else {
+		ctx.Flash.Success(ctx.Tr("repo.settings.update_avatar_success"))
+	}
+	ctx.Redirect(ctx.Repo.RepoLink + "/settings")
+}
+
+// SettingsDeleteAvatar delete repository avatar
+func SettingsDeleteAvatar(ctx *context.Context) {
+	if err := repo_service.DeleteAvatar(ctx, ctx.Repo.Repository); err != nil {
+		ctx.Flash.Error(fmt.Sprintf("DeleteAvatar: %v", err))
+	}
+	ctx.Redirect(ctx.Repo.RepoLink + "/settings")
+}