Support for --distdir with multiple versions

## Use-Case:
Using [--distdir](https://docs.bazel.build/versions/master/command-line-reference.html#flag--distdir) to achieve an [airgapped build](https://docs.bazel.build/versions/master/guide.html#running-bazel-in-an-airgapped-environment).

Building different bazel versions but with the requirement to use a distdir.

If bazel/bazelisk is cached inside a container for an offline build and used with different versions.
The distdir can be cached in that container alongside the different bazel-versions.

## The idea:
To have something that tells bazelisk to pass a different `--distdir` to bazel depending on the detected version.
e.g. Appending the version to the path passed and forwarding that to bazel
```bash
export BAZELISK_APPEND_DISTDIR_VERSION=
export USE_BAZEL_VERSION=4.0.0
bazelisk build ... --distdir=/var/bazel/distfiles
# would yield the actual call
bazel build ... --distdir=/var/bazel/distfiles/4.0.0
```

Start by reading Bazelisk's handling of USE_BAZEL_VERSION and forwarded --distdir arguments, then compare the requested example for versions 4.0.0 and multiple cached Bazel versions. Done means a configured distdir is version-specific when requested, while the resulting Bazel invocation preserves the expected flag behavior.

Written by the indexing model from the issue text.