tailscale: update tailfs functions and vars to use drive naming (#11597)

This change updates all tailfs functions and the majority of the tailfs
variables to use the new drive naming.

Updates tailscale/corp#16827

Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>

drive/local.go

@@ -2,10 +2,10 @@
 // SPDX-License-Identifier: BSD-3-Clause
 
 // Package drive provides a filesystem that allows sharing folders between
-// Tailscale nodes using WebDAV. The actual implementation of the core drive
+// Tailscale nodes using WebDAV. The actual implementation of the core Taildrive
 // functionality lives in package driveimpl. These packages are separated to
-// allow users of drive to refer to the interfaces without having a hard
-// dependency on drive, so that programs which don't actually use drive can
+// allow users of Taildrive to refer to the interfaces without having a hard
+// dependency on Taildrive, so that programs which don't actually use Taildrive can
 // avoid its transitive dependencies.
 package drive
 
@@ -14,15 +14,15 @@ import (
 	"net/http"
 )
 
-// Remote represents a remote TailFS node.
+// Remote represents a remote Taildrive node.
 type Remote struct {
 	Name      string
 	URL       string
 	Available func() bool
 }
 
-// FileSystemForLocal is the TailFS filesystem exposed to local clients. It
-// provides a unified WebDAV interface to remote TailFS shares on other nodes.
+// FileSystemForLocal is the Taildrive filesystem exposed to local clients. It
+// provides a unified WebDAV interface to remote Taildrive shares on other nodes.
 type FileSystemForLocal interface {
 	// HandleConn handles connections from local WebDAV clients
 	HandleConn(conn net.Conn, remoteAddr net.Addr) error