feat: make some private methods public to give callers more flexibility. (#450)

This allows to implement the fetch-negotiation part oneself and break
free from constraints of the delegate.

Author: Byron

git-protocol/src/fetch/arguments/blocking_io.rs

@@ -5,7 +5,8 @@ use git_transport::{client, client::TransportV2Ext};
 use crate::fetch::{Arguments, Command};
 
 impl Arguments {
-    pub(crate) fn send<'a, T: client::Transport + 'a>(
+    /// Send fetch arguments to the server, and indicate this is the end of negotiations only if `add_done_argument` is present.
+    pub fn send<'a, T: client::Transport + 'a>(
         &mut self,
         transport: &'a mut T,
         add_done_argument: bool,

git-protocol/src/fetch/arguments/mod.rs

@@ -125,8 +125,10 @@ impl Arguments {
     fn prefixed(&mut self, prefix: &str, value: impl fmt::Display) {
         self.args.push(format!("{}{}", prefix, value).into());
     }
+    /// Create a new instance to help setting up arguments to send to the server as part of a `fetch` operation
+    /// for which `features` are the available and configured features to use.
     #[cfg(any(feature = "async-client", feature = "blocking-client"))]
-    pub(crate) fn new(version: git_transport::Protocol, features: Vec<crate::fetch::command::Feature>) -> Self {
+    pub fn new(version: git_transport::Protocol, features: Vec<crate::fetch::command::Feature>) -> Self {
         use crate::fetch::Command;
         let has = |name: &str| features.iter().any(|f| f.0 == name);
         let filter = has("filter");

git-protocol/src/fetch/command.rs

@@ -112,8 +112,9 @@ mod with_io {
             }
         }
 
-        /// Turns on all modern features for V1 and all supported features for V2.
-        pub(crate) fn default_features(
+        /// Turns on all modern features for V1 and all supported features for V2, returning them as a vector of features.
+        /// Note that this is the basis for any fetch operation as these features fulfil basic requirements and reasonably up-to-date servers.
+        pub fn default_features(
             &self,
             version: git_transport::Protocol,
             server_capabilities: &Capabilities,