Dump: add output format tar and output to stdout (#10376)

* Dump: Use mholt/archive/v3 to support tar including many compressions

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: Allow dump output to stdout

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: Fixed bug present since #6677 where SessionConfig.Provider is never "file"

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: never pack RepoRootPath, LFS.ContentPath and LogRootPath when they are below AppDataPath

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: also dump LFS (fixes #10058)

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: never dump CustomPath if CustomPath is a subdir of or equal to AppDataPath (fixes #10365)

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Use log.Info instead of fmt.Fprintf

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* import ordering

* make fmt

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Matti R <matti@mdranta.net>

vendor/github.com/mholt/archiver/v3/filecompressor.go

@@ -0,0 +1,67 @@
+package archiver
+
+import (
+	"fmt"
+	"os"
+)
+
+// FileCompressor can compress and decompress single files.
+type FileCompressor struct {
+	Compressor
+	Decompressor
+
+	// Whether to overwrite existing files when creating files.
+	OverwriteExisting bool
+}
+
+// CompressFile reads the source file and compresses it to destination.
+// The destination must have a matching extension.
+func (fc FileCompressor) CompressFile(source, destination string) error {
+	if err := fc.CheckExt(destination); err != nil {
+		return err
+	}
+	if fc.Compressor == nil {
+		return fmt.Errorf("no compressor specified")
+	}
+	if !fc.OverwriteExisting && fileExists(destination) {
+		return fmt.Errorf("file exists: %s", destination)
+	}
+
+	in, err := os.Open(source)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	out, err := os.Create(destination)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	return fc.Compress(in, out)
+}
+
+// DecompressFile reads the source file and decompresses it to destination.
+func (fc FileCompressor) DecompressFile(source, destination string) error {
+	if fc.Decompressor == nil {
+		return fmt.Errorf("no decompressor specified")
+	}
+	if !fc.OverwriteExisting && fileExists(destination) {
+		return fmt.Errorf("file exists: %s", destination)
+	}
+
+	in, err := os.Open(source)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	out, err := os.Create(destination)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	return fc.Decompress(in, out)
+}