option_parser: Add support for adding from a slice

Add an OptionParser::add_all method that takes a slice of option names
and use that to add to the set of parameters that the parser works on.

Signed-off-by: Rob Bradford <rbradford@meta.com>

option_parser/src/lib.rs

@@ -148,6 +148,14 @@ impl OptionParser {
         self
     }
 
+    pub fn add_all(&mut self, options: &[&str]) -> &mut Self {
+        for option in options {
+            self.add(option);
+        }
+
+        self
+    }
+
     pub fn add_valueless(&mut self, option: &str) -> &mut Self {
         self.options.insert(
             option.to_owned(),