refactor: optimize vmx encoding buffer writes

Write VMX entries directly into the output buffer instead of formatting an intermediate string first. This avoids unnecessary allocations while preserving the same encoded output.

Signed-off-by: Ryan Johnson <ryan@tenthirtyam.org>

Author: tenthirtyam

builder/vmware/common/vmx.go

@@ -73,7 +73,7 @@ func EncodeVMX(contents map[string]string) string {
 		for _, c := range caseSensitive {
 			key = strings.Replace(key, strings.ToLower(c), c, 1)
 		}
-		buf.WriteString(fmt.Sprintf(pat, key, contents[k]))
+		fmt.Fprintf(&buf, pat, key, contents[k])
 	}
 
 	return buf.String()