[build] MVP for building with bazel (#6994)

wpiunits/BUILD.bazel

@@ -0,0 +1,17 @@
+load("@rules_java//java:defs.bzl", "java_binary", "java_library")
+
+java_library(
+    name = "wpiunits",
+    srcs = glob(["src/main/java/**/*.java"]) + glob(["src/generated/main/java/**/*.java"]),
+    visibility = ["//visibility:public"],
+    deps = [],
+)
+
+java_binary(
+    name = "DevMain-Java",
+    srcs = ["src/dev/java/edu/wpi/first/units/DevMain.java"],
+    main_class = "edu.wpi.first.units.DevMain",
+    deps = [
+        ":wpiunits",
+    ],
+)