Impl TryFrom<fmt::Arguments<'a>> for ArrayString

Shortcut for

```
use fmt::Write;
let mut v = Self::new();
v.write_fmt(f).map_err(|e| CapacityError::new(e))?;
```

src/array_string.rs

@@ -594,3 +594,17 @@ where
         Ok(v)
     }
 }
+
+impl<'a, A> TryFrom<fmt::Arguments<'a>> for ArrayString<A>
+where
+    A: Array<Item = u8> + Copy
+{
+    type Error = CapacityError<fmt::Error>;
+
+    fn try_from(f: fmt::Arguments<'a>) -> Result<Self, Self::Error> {
+        use fmt::Write;
+        let mut v = Self::new();
+        v.write_fmt(f).map_err(|e| CapacityError::new(e))?;
+        Ok(v)
+    }
+}