Getting git repository as dependency does not include git submodules

Prerequisites

Please put an X between the brackets as you perform the following steps:

• [x ] Check that your issue is not already filed:
  https://github.com/leanprover/lean4/issues
• [ x] Reduce the issue to a minimal, self-contained, reproducible test case.
  Avoid dependencies to Mathlib or Batteries.
• [x ] Test your test case against the latest nightly release, for example on
  https://live.lean-lang.org/#project=lean-nightly
  (You can also use the settings there to switch to “Lean nightly”)

Description

Getting a git repository as a dependency does not include git submodules

Lean does not call git clone --recursive when cloning a git repository
https://github.com/leanprover/lean4/blob/c6abc3c0368e10c49e9762fda1819ad0e95c9bb0/src/lake/Lake/Util/Git.lean#L65-L66

Context

#new members > Does importing dependency as git repository clone submodules

Steps to Reproduce

1. Add git repository as dependency

Expected behavior: [Clear and concise description of what you expect to happen]
Includes submodule dependency

Actual behavior: [Clear and concise description of what actually happens]
Does not include submodule dependency

Versions

4.23, nightly

[Output of #version or #eval Lean.versionString]
[OS version, if not using live.lean-lang.org.]

Additional Information

[Additional information, configuration or data that might be necessary to reproduce the issue]

Impact

Add 👍 to issues you consider important. If others are impacted by this issue, please ask them to add 👍 to it.

Start at src/lake/Lake/Util/Git.lean around lines 65–66 and inspect how Lake clones git dependencies. Reproduce the dependency setup from the issue with a repository containing a submodule, then verify that fetching the dependency also includes the submodule.