Move convert package to services (#22264)

Addition to #22256

The `convert` package relies heavily on different models which is
[disallowed by our definition of
modules](https://github.com/go-gitea/gitea/blob/main/CONTRIBUTING.md#design-guideline).
This helps to prevent possible import cycles.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

services/convert/status.go

@@ -0,0 +1,57 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package convert
+
+import (
+	"context"
+
+	git_model "code.gitea.io/gitea/models/git"
+	user_model "code.gitea.io/gitea/models/user"
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// ToCommitStatus converts git_model.CommitStatus to api.CommitStatus
+func ToCommitStatus(ctx context.Context, status *git_model.CommitStatus) *api.CommitStatus {
+	apiStatus := &api.CommitStatus{
+		Created:     status.CreatedUnix.AsTime(),
+		Updated:     status.CreatedUnix.AsTime(),
+		State:       status.State,
+		TargetURL:   status.TargetURL,
+		Description: status.Description,
+		ID:          status.Index,
+		URL:         status.APIURL(),
+		Context:     status.Context,
+	}
+
+	if status.CreatorID != 0 {
+		creator, _ := user_model.GetUserByID(ctx, status.CreatorID)
+		apiStatus.Creator = ToUser(creator, nil)
+	}
+
+	return apiStatus
+}
+
+// ToCombinedStatus converts List of CommitStatus to a CombinedStatus
+func ToCombinedStatus(ctx context.Context, statuses []*git_model.CommitStatus, repo *api.Repository) *api.CombinedStatus {
+	if len(statuses) == 0 {
+		return nil
+	}
+
+	retStatus := &api.CombinedStatus{
+		SHA:        statuses[0].SHA,
+		TotalCount: len(statuses),
+		Repository: repo,
+		URL:        "",
+	}
+
+	retStatus.Statuses = make([]*api.CommitStatus, 0, len(statuses))
+	for _, status := range statuses {
+		retStatus.Statuses = append(retStatus.Statuses, ToCommitStatus(ctx, status))
+		if status.State.NoBetterThan(retStatus.State) {
+			retStatus.State = status.State
+		}
+	}
+
+	return retStatus
+}