feat(migrations): add migration from Bitbucket Server (Data Center) (#39913)

Add migration from Bitbucket Server (Data Center). It has no issues,
wiki, milestones or releases, so those are not offered.

Migrated: git data with tags and LFS, and pull requests with state,
draft flag, merge commit/base, comments, approvals and inline code
comments including resolved threads. Multi-line ranges become a `Lines
a-b:` text prefix, as Gitea anchors code comments to one line. Auth is
an HTTP access token (personal, project or repository) or
username/password; 429 responses are retried.

Changes outside the downloader:
- `ReviewComment.Resolved`, applied by the uploader.
- The uploader creates a fork PR's head branch from its head commit when
already in the repository, instead of fetching the fork (Bitbucket keeps
it in `refs/pull-requests/<id>/from`; private forks need credentials).

Tested with unit tests, responses recorded from Bitbucket 10.5.1, and an
end-to-end migration. Independent of
https://github.com/go-gitea/gitea/pull/38607 (Bitbucket Cloud); the
service type enum value needs adjusting for whichever lands second.

---------

Co-authored-by: bircni <bircni@icloud.com>

modules/migration/review.go

@@ -62,6 +62,7 @@ type ReviewComment struct {
 	Line      int
 	CommitID  string `yaml:"commit_id"`
 	PosterID  int64  `yaml:"poster_id"`
+	Resolved  bool   // the conversation of this (first) comment is resolved
 	Reactions []*Reaction
 	CreatedAt time.Time `yaml:"created_at"`
 	UpdatedAt time.Time `yaml:"updated_at"`

modules/structs/repo.go

@@ -347,22 +347,23 @@ type GitServiceType int
 
 // enumerate all GitServiceType
 const (
-	NotMigrated       GitServiceType = iota // 0 not migrated from external sites
-	PlainGitService                         // 1 plain git service
-	GithubService                           // 2 github.com
-	GiteaService                            // 3 gitea service
-	GitlabService                           // 4 gitlab service
-	GogsService                             // 5 gogs service
-	OneDevService                           // 6 onedev service
-	GitBucketService                        // 7 gitbucket service
-	CodebaseService                         // 8 codebase service
-	CodeCommitService                       // 9 codecommit service
+	NotMigrated            GitServiceType = iota // 0 not migrated from external sites
+	PlainGitService                              // 1 plain git service
+	GithubService                                // 2 github.com
+	GiteaService                                 // 3 gitea service
+	GitlabService                                // 4 gitlab service
+	GogsService                                  // 5 gogs service
+	OneDevService                                // 6 onedev service
+	GitBucketService                             // 7 gitbucket service
+	CodebaseService                              // 8 codebase service
+	CodeCommitService                            // 9 codecommit service
+	BitbucketServerService                       // 10 bitbucket server (data center) service
 )
 
 // Name represents the service type's name
 // WARNING: the name has to be equal to that on goth's library
 func (gt GitServiceType) Name() string {
-	return strings.ToLower(gt.Title())
+	return strings.ToLower(strings.ReplaceAll(gt.Title(), " ", ""))
 }
 
 // Title represents the service type's proper title
@@ -384,12 +385,32 @@ func (gt GitServiceType) Title() string {
 		return "Codebase"
 	case CodeCommitService:
 		return "CodeCommit"
+	case BitbucketServerService:
+		return "Bitbucket Server"
 	case PlainGitService:
 		return "Git"
 	}
 	return ""
 }
 
+// Variants returns the hosting options of gt's provider, which share one entry on the migrate page
+func (gt GitServiceType) Variants() []GitServiceType {
+	switch gt {
+	case BitbucketServerService:
+		return []GitServiceType{BitbucketServerService}
+	}
+	return nil
+}
+
+// ProviderTitle returns the title of gt's entry on the migrate page
+func (gt GitServiceType) ProviderTitle() string {
+	switch gt {
+	case BitbucketServerService:
+		return "Bitbucket"
+	}
+	return gt.Title()
+}
+
 // MigrateRepoOptions options for migrating repository's
 // this is used to interact with api v1
 type MigrateRepoOptions struct {
@@ -402,7 +423,7 @@ type MigrateRepoOptions struct {
 	// required: true
 	RepoName string `json:"repo_name" binding:"Required;AlphaDashDot;MaxSize(100)"`
 
-	// enum: ["git","github","gitea","gitlab","gogs","onedev","gitbucket","codebase","codecommit"]
+	// enum: ["git","github","gitea","gitlab","gogs","onedev","gitbucket","codebase","codecommit","bitbucketserver"]
 	Service      string `json:"service"`
 	AuthUsername string `json:"auth_username"`
 	AuthPassword string `json:"auth_password"`
@@ -445,6 +466,7 @@ var SupportedFullGitService = []GitServiceType{
 	GitBucketService,
 	CodebaseService,
 	CodeCommitService,
+	BitbucketServerService,
 }
 
 // RepoTransfer represents a pending repo transfer