Embed the install manifests in flux binary

- add make target for generating the install manifests using kustomize
- embed the generated manifests in flux binary
- the install and bootstrap commands default to using the embedded manifests
- download the install manifests from GitHub only if the install/bootstrap version arg is set

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

pkg/manifestgen/install/install_test.go

@@ -25,7 +25,7 @@ import (
 func TestGenerate(t *testing.T) {
 	opts := MakeDefaultOptions()
 	opts.TolerationKeys = []string{"node.kubernetes.io/controllers"}
-	output, err := Generate(opts)
+	output, err := Generate(opts, "")
 	if err != nil {
 		t.Fatal(err)
 	}