[antlir] Add feature.run as an alias for feature.genrule

Summary:
**This diff**

Adds a simple `run` alias for `genrule` in the Antlir features.

**Why**

Lots of people are used to `RUN` command in docker files that does the same as `genrule` in our case.

Test Plan: reviewbylookingveryhard

Reviewed By: vmagro

Differential Revision: D83288955

fbshipit-source-id: 87babe8278cd0116747cdc13b678c51187cc5f0d

Author: sergeyfd

antlir/antlir2/bzl/feature/defs.bzl

@@ -43,6 +43,7 @@ feature = struct(
     rpms_remove = rpms_remove,
     rpms_remove_if_exists = rpms_remove_if_exists,
     rpms_upgrade = rpms_upgrade,
+    run = genrule,
     dnf_module_enable = dnf_module_enable,
     ensure_file_symlink = ensure_file_symlink,
     ensure_dir_symlink = ensure_dir_symlink,