Add pure SSH LFS support (#31516)

Fixes #17554
/claim #17554

Docs PR https://gitea.com/gitea/docs/pulls/49

To test, run pushes like: `GIT_TRACE=1` git push. The trace output
should mention "pure SSH connection".

modules/lfstransfer/logger.go

@@ -0,0 +1,21 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package lfstransfer
+
+import (
+	"github.com/charmbracelet/git-lfs-transfer/transfer"
+)
+
+var _ transfer.Logger = (*GiteaLogger)(nil)
+
+// noop logger for passing into transfer
+type GiteaLogger struct{}
+
+func newLogger() transfer.Logger {
+	return &GiteaLogger{}
+}
+
+// Log implements transfer.Logger
+func (g *GiteaLogger) Log(msg string, itms ...any) {
+}