third_party/edk2: use toolchain-bundle for edk2 build

This moves the build into a custom rule instead of a genrule.
This also adds the AARCH64 build and renames the files to be more
generic

Change-Id: If6e3cecaf4011e2e39f13b1d40bcc7060cee3afb
Reviewed-on: https://review.monogon.dev/c/monogon/+/4154
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/test/launch/cluster.go b/metropolis/test/launch/cluster.go
index d2bbb4b..af15564 100644
--- a/metropolis/test/launch/cluster.go
+++ b/metropolis/test/launch/cluster.go
@@ -322,7 +322,7 @@
 	}
 
 	tpmSocketPath := filepath.Join(r.sd, "tpm-socket")
-	fwVarPath := filepath.Join(r.ld, "OVMF_VARS.fd")
+	fwVarPath := filepath.Join(r.ld, "VARS.fd")
 	storagePath := filepath.Join(r.ld, "image.img")
 	qemuArgs := []string{
 		"-machine", "q35",