feat: add a builder() method to HttpsConnector

[Fishrock123]

It's become very idiomatic to have the builder api be accessed this way.

[Fishrock123]

Not quite sure how to make rustdoc link those references correctly? 😕

[djc]

See #260 (comment).

[Fishrock123]

This PR could just as well be completely unrelated from the other two.

This is not necessary but is a common API idom for builder APIs in Rust.

[djc]

Fair point! I think this is a good change.

Tiny nit: as a constructor of sorts (even if indirectly), I would prefer we move builder() before enforce_https().

[cpu]

Thanks, this looks good to me modulo the CI docs failure getting fixed.

Not quite sure how to make rustdoc link those references correctly?

I think this diff will do the trick:

diff --git a/src/connector.rs b/src/connector.rs
index 103dede..5b975e0 100644
--- a/src/connector.rs
+++ b/src/connector.rs
@@ -35,9 +35,9 @@ impl<T> HttpsConnector<T> {
         self.force_https = true;
     }

-    /// Creates a [`builder::HttpsConnectorBuilder`] to configure a `HttpsConnector`.
+    /// Creates a [`crate::HttpsConnectorBuilder`] to configure a `HttpsConnector`.
     ///
-    /// This is the same as [`builder::HttpsConnectorBuilder::new()`].
+    /// This is the same as [`crate::HttpsConnectorBuilder::new()`].
     pub fn builder() -> builder::ConnectorBuilder<builder::WantsTlsConfig> {
         builder::ConnectorBuilder::new()
     }