fix: support http basic auth for curl downloader (#268)

Co-authored-by: João Guerra <[email protected]>

oci/private/download.bzl

@@ -1,12 +1,19 @@
 "Downloader functions "
 
+load("@aspect_bazel_lib//lib:base64.bzl", "base64")
+
 def _auth_to_header(url, auth):
     for auth_url in auth:
         if auth_url == url:
             auth_val = auth[auth_url]
 
-            # TODO: basic type
-            if auth_val["type"] == "pattern":
+            if auth_val["type"] == "basic":
+                credentials = base64.encode("{}:{}".format(auth_val["login"], auth_val["password"]))
+                return [
+                    "--header",
+                    "Authorization: Basic {}".format(credentials),
+                ]
+            elif auth_val["type"] == "pattern":
                 token = auth_val["pattern"].replace("<password>", auth_val["password"])
                 return [
                     "--header",