This removes the need to source env.{sh,fish} when working with hscloud.
This is done by:
1. Implementing a Go library to reliably detect the location of the
active hscloud checkout. That in turn is enabled by
BUILD_WORKSPACE_DIRECTORY being now a thing in Bazel.
2. Creating a tool `hscloud`, with a command `hscloud workspace` that
returns the workspace path.
3. Wrapping this tool to be accessible from Python and Bash.
4. Bumping all users of hscloud_root to use either the Go library or
one of the two implemented wrappers.
We also drive-by replace tools/install.sh to be a proper sh_binary, and
make it yell at people if it isn't being ran as `bazel run
//tools:install`.
Finally, we also drive-by delete cluster/tools/nixops.sh which was never used.
Change-Id: I7873714319bfc38bbb930b05baa605c5aa36470a
Reviewed-on: https://gerrit.hackerspace.pl/c/hscloud/+/1169
Reviewed-by: informatic <informatic@hackerspace.pl>
radex
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