Review tweaks

* Update to use defs.bzl
* Fix up some tests
* Remove pseudo-attempt at bootstrapping

Author: illicitonion

cargo/crate_universe_resolver/src/templates/crate.BUILD.template

@@ -1,8 +1,9 @@
 # buildifier: disable=load
 load(
-    "@rules_rust//rust:rust.bzl",
+    "@rules_rust//rust:defs.bzl",
     "rust_binary",
     "rust_library",
+    "rust_proc_macro",
     "rust_test",
 )
 

cargo/crate_universe_resolver/src/templates/partials/rust_library.template

@@ -11,9 +11,12 @@ alias(
 
 {% endif -%}
 # buildifier: leave-alone
+{%- if target.kind == "proc-macro" %}
+rust_proc_macro(
+{%- else %}
 rust_library(
+{%- endif %}
     name = "{{ target_name_sanitized }}",
-    crate_type = "{{ target.kind }}",
     deps = [
         {%- if crate.build_script_target %}
         ":{{ crate_name_sanitized }}_build_script",