Add bzlmod module file

[hanneskaeufler]

Motivation:
bazelbuild/bazel-central-registry#124

Open questions:

• Is the googletest project willing to maintain the bzlmod file?

[hanneskaeufler]

In order not to have to maintain a version number multiple times (or at all), it seems to be a somewhat often used practice to have 0.0.0 here and just increment the version number in the bazel central registry.

[Vertexwahn]

The version attribute is optional - maybe leave it out, instead of using 0.0.0

[hanneskaeufler]

@derekmauro Anything I can do to move this forward? thanks!

[Vertexwahn]

@derekmauro Can we bring this forward?

[Vertexwahn]

@derekmauro Please review!

[derekmauro]

I'm not really sure how this is supposed to work.

We prefer to live at head. This means, for example, that sometimes we might use a feature in the latest head version of Abseil that isn't part of any release. How is bzlmod supposed to deal with this?

[Vertexwahn]

@derekmauro Good point! There is archive_override to override a specific version with a new one: #4368

[hanneskaeufler]

Closing in favor of #4368, thanks for picking this up Vertexwahn!