Pass along output_base to bazel invocations in gen_rust_project

[alexkirsz]

If a custom Bazel output_base is passed to gen_rust_project through the --output-base CLI option, the tool should pass along this output_base to all downstream Bazel invocations.

In this case, there are two:

bazel info

and

bazel build --aspects={}//rust:defs.bzl%rust_analyzer_aspect

Without this, invoking the following results in an empty rust-project.json:

bazel --output_base=$OUTPUT_BASE run @rules_rust//tools/rust_analyzer:gen_rust_project -- --output-base=$OUTPUT_BASE -- $TARGETS

It would be even better if the tool could somehow read its output_base from the original bazel invocation.