[antlir2][build_appliance] add btrfs-progs

Summary:
Install `btrfs-progs` into the build appliance for btrfs loopback packaging
purposes.

This gives us the upstream `mkfs.btrfs`/`btrfstune` in OSS builds, and the fbsource
copy (which is more up to date than the release in C9 at the time of this diff).

Test Plan: Next diff

Reviewed By: naveedgol

Differential Revision: D69810767

fbshipit-source-id: 7ea2372b7f258bab04125c29d1e03167be83271c

antlir/antlir2/antlir2_packager/BUCK

@@ -79,6 +79,23 @@ feature.new(
                 "erofs-utils",
             ]),
         }),
+        internal_external(
+            fb = [
+                feature.install(
+                    src = "fbsource//third-party/btrfs-progs:btrfs",
+                    dst = "/usr/local/bin/btrfs",
+                ),
+                feature.install(
+                    src = "fbsource//third-party/btrfs-progs:btrfstune",
+                    dst = "/usr/local/bin/btrfstune",
+                ),
+                feature.install(
+                    src = "fbsource//third-party/btrfs-progs:mkfs.btrfs",
+                    dst = "/usr/local/bin/mkfs.btrfs",
+                ),
+            ],
+            oss = feature.rpms_install(rpms = ["btrfs-progs"]),
+        ),
     ],
     visibility = ["//antlir/antlir2/build_appliance/..."],
 )