Bazel client: warn if output paths have space
Bazel client: warn if output paths have space

Warn the user if output_user_root or output_base
have a space character, because that probably
breaks the build.

This is a warning and not a hard error, because
some Bazel functions ("bazel info" for example)
work fine with such paths.

Common causes for bad output paths are:
- user name having a space (on Windows)
- bad --output_user_root and/or --output_base
  value

Fixes https://github.com/bazelbuild/bazel/issues/7979

Closes #8845.

PiperOrigin-RevId: 257382528

dslomov/bazel,davidzchen/bazel,werkt/bazel,meteorcloudy/bazel,ulfjack/bazel,bazelbuild/bazel,dslomov/bazel,ulfjack/bazel,ButterflyNetwork/bazel,dslomov/bazel,ulfjack/bazel,katre/bazel,cushon/bazel,cushon/bazel,dslomov/bazel-windows,dslomov/bazel,bazelbuild/bazel,ulfjack/bazel,safarmer/bazel,twitter-forks/bazel,perezd/bazel,dslomov/bazel-windows,katre/bazel,aehlig/bazel,meteorcloudy/bazel,katre/bazel,dslomov/bazel-windows,davidzchen/bazel,safarmer/bazel,ButterflyNetwork/bazel,ulfjack/bazel,safarmer/bazel,werkt/bazel,ulfjack/bazel,twitter-forks/bazel,akira-baruah/bazel,akira-baruah/bazel,werkt/bazel,dslomov/bazel-windows,cushon/bazel,dslomov/bazel,dslomov/bazel,werkt/bazel,akira-baruah/bazel,perezd/bazel,aehlig/bazel,twitter-forks/bazel,meteorcloudy/bazel,perezd/bazel,katre/bazel,katre/bazel,ButterflyNetwork/bazel,aehlig/bazel,werkt/bazel,twitter-forks/bazel,ButterflyNetwork/bazel,dslomov/bazel-windows,meteorcloudy/bazel,akira-baruah/bazel,twitter-forks/bazel,bazelbuild/bazel,meteorcloudy/bazel,davidzchen/bazel,aehlig/bazel,davidzchen/bazel,ulfjack/bazel,twitter-forks/bazel,werkt/bazel,cushon/bazel,safarmer/bazel,dslomov/bazel,twitter-forks/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,aehlig/bazel,davidzchen/bazel,perezd/bazel,dslomov/bazel-windows,aehlig/bazel,katre/bazel,cushon/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,bazelbuild/bazel,meteorcloudy/bazel,perezd/bazel,perezd/bazel,safarmer/bazel,akira-baruah/bazel,perezd/bazel,cushon/bazel,safarmer/bazel,akira-baruah/bazel,davidzchen/bazel,bazelbuild/bazel,aehlig/bazel,davidzchen/bazel