It can only pack to zip for now (packing to tar is
not trivial and I haven't figured it out yet).

This allows building //:bazel-distfile on Windows.
Previously it was either timing out or taking so
long that it was unbearable (over 10 minutes).
I never waited long enough to see it build.

The new Python version runs under just a few
seconds.

Change-Id: I3264eb7132dd58c581c4216e5bbab035a79d716d
PiperOrigin-RevId: 164954162

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MOS_MIGRATED_REVID=140137447

The docker tests in //tools/cpp/test still assume that the sources
are enough to just compile.sh to bootstrap a bazel binary. Fix this,
by using the distribution archive instead.

While there, also add a target for the distribution archive as tar.

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Change-Id: Ic31bb95da0165f83a14537a1719c27e5067d0d65
Reviewed-on: https://cr.bazel.build/7531
MOS_MIGRATED_REVID=140134322

...containing, besides the original sources, all generated machine-independent
files needed for creating a bootstrap bazel without the need of having a protoc
installed.

--
Change-Id: Ib90e7896615b4067175a23fe2c942dbac4b71e4a
Reviewed-on: https://bazel-review.googlesource.com/#/c/6730
MOS_MIGRATED_REVID=136910561