Bazel/Blaze BUILD

Hey Googlers!

Any chance you'd be down to release the Blaze/Bazel (Blazel!) BUILD files for this code? Would be handy to those of us building with Bazel, and I assume you've got them internally already. I think the only external dep, PromisesObjC, already has released theirs, which should keep things pretty easy.

If useful, here's the start of one I spun up for the subspecs I needed:

```Starlark
# Created referencing https://github.com/google/GoogleUtilities/blob/406c461ae85acbc2da327f13619ffa187f7b729e/GoogleUtilities.podspec

objc_library(
name = "Environment",
hdrs = glob(["GoogleUtilities/Environment/Public/GoogleUtilities/*.h"]),
includes = ["GoogleUtilities/Environment/Public"],
visibility = ["//visibility:public"],

srcs = glob(["GoogleUtilities/Environment/**/*.m", "GoogleUtilities/Environment/**/*.h"]),
deps = ["@GooglePromises//:FBLPromises", ":IsAppEncrypted"],
sdk_frameworks = ["Security"],
)

objc_library(
name = "Logger",
hdrs = glob(["GoogleUtilities/Logger/Public/GoogleUtilities/*.h"]),
includes = ["GoogleUtilities/Logger/Public"],
visibility = ["//visibility:public"],

srcs = glob(["GoogleUtilities/Logger/**/*.m", "GoogleUtilities/Logger/**/*.h"]),
deps = [":Environment"],
)

objc_library(
name = "IsAppEncrypted",
hdrs = ["third_party/IsAppEncrypted/Public/IsAppEncrypted.h"],
srcs = ["third_party/IsAppEncrypted/IsAppEncrypted.m"],
)
```

Thanks for your consideration!
Chris
(ex-Googler)