feat: expose ::new for Extensions, Header, and Values

based on: https://github.com/http-rs/http-types/pull/320/files by @jbr

Author: OneOfOne

src/extensions.rs

@@ -21,7 +21,7 @@ pub struct Extensions {
 impl Extensions {
     /// Create an empty `Extensions`.
     #[inline]
-    pub(crate) fn new() -> Self {
+    pub fn new() -> Self {
         Self { map: None }
     }
 

src/headers/headers.rs

@@ -32,7 +32,7 @@ pub struct Headers {
 
 impl Headers {
     /// Create a new instance.
-    pub(crate) fn new() -> Self {
+    pub fn new() -> Self {
         Self { headers: HashMap::new() }
     }
 

src/headers/values.rs

@@ -13,7 +13,7 @@ pub struct Values<'a> {
 
 impl<'a> Values<'a> {
     /// Constructor for `Headers`.
-    pub(crate) fn new(inner: hash_map::Values<'a, HeaderName, HeaderValues>) -> Self {
+    pub fn new(inner: hash_map::Values<'a, HeaderName, HeaderValues>) -> Self {
         Self {
             inner: Some(inner),
             slot: None,
@@ -22,7 +22,7 @@ impl<'a> Values<'a> {
     }
 
     /// Constructor for `HeaderValues`.
-    pub(crate) fn new_values(values: &'a HeaderValues) -> Self {
+    pub fn new_values(values: &'a HeaderValues) -> Self {
         Self {
             inner: None,
             slot: Some(values),