## Description

There were two filesystem races going on: One for access to
`install_dir` (this was an existing problem) and one for the lock file
(new problem). This PR addresses both, by using
`BuildConfig::new_for_testing` in `cli_tests` and ensuring that the lock
file gets stored in the temporary directory rather than the package root
in tests that use `BuildConfig::new_for_testing`.

## Test Plan

```
$ env RUST_LOG=off MSIM_TEST_NUM=10 cargo simtest
```