arm64 support with grub-efi

* build / convert: add `--platform` flag to support linux/amd64 &
linux/arm64
* build: add `--pull` flag
* run/hetzner: add `--type` flag to select server type
* run/hetzner: add `--location` flag to select server location

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

convert_options.go

@@ -32,6 +32,8 @@ type convertOptions struct {
 	luksPassword string
 
 	keepCache bool
+	platform  string
+	pull      bool
 }
 
 func (o *convertOptions) hasGrubBIOS() bool {
@@ -113,3 +115,15 @@ func WithKeepCache(b bool) ConvertOption {
 		o.keepCache = b
 	}
 }
+
+func WithPlatform(platform string) ConvertOption {
+	return func(o *convertOptions) {
+		o.platform = platform
+	}
+}
+
+func WithPull(b bool) ConvertOption {
+	return func(o *convertOptions) {
+		o.pull = b
+	}
+}