initial project setup

In this commit we set up the basic project structure.
- An integ crate that will serve as our driver for integration testing.
  Eventually this will be used to set up and run Bottlerocket instances
  that the updater can be tested against.
- The updater crate. This will become the binary that checks and updates
  Bottlerocket instances.
- A simple Dockerfile and Makefile, since we will be deploying the
  updater to Fargate.

updater has a lib.rs file so that we can re-use some code from updater
in integ, and so that updater can have a useful tests directory.

Makefile

@@ -0,0 +1,7 @@
+.PHONY: image
+image:
+	docker build -t bottlerocket-update-operator:latest "${PWD}/updater"
+
+.PHONY: x86_64-unknown-linux-musl
+x86_64-unknown-linux-musl:
+	docker build -t bottlerocket-update-operator:latest "${PWD}/updater"