fix: use Must() to cache executable path

This commit uses Must() to cache the executable path and makes it overridable in tests.

Signed-off-by: Konikz <konikz@github.com>

Author: Konikz

pkg/usrlocalsharelima/usrlocalsharelima.go

@@ -13,14 +13,15 @@ import (
 
 	"github.com/lima-vm/lima/pkg/debugutil"
 	"github.com/lima-vm/lima/pkg/limayaml"
+	. "github.com/lima-vm/lima/pkg/must"
 	"github.com/sirupsen/logrus"
 )
 
+// executable is a variable that can be overridden in tests.
+var executable = os.Executable
+
 func Dir() (string, error) {
-	self, err := os.Executable()
-	if err != nil {
-		return "", err
-	}
+	self := Must(executable())
 	selfSt, err := os.Stat(self)
 	if err != nil {
 		return "", err