Use git lfs for stage0 to save space

[Anderssorby]

Suggestion

The lean4 repository takes up a large amount of space ~1.3GiB and that makes the experience less than ideal.
Since the stage0 is just generated and treated as binary data I suggest putting it into tracking by git-lfs to speed up downloads and reduce space needed. It tracks content hashes and registers and stores the data separately avoiding download of a large amount of data.
https://git-lfs.com/

git lfs track stage0

When downloading a fresh repo remember to git lfs checkout.

What do you think?

[Kha]

Some commments on LFS, mostly negative: https://news.ycombinator.com/item?id=27134972

to speed up downloads and reduce space needed

A far simpler solution for that would be to use a partial clone. git clone --filter=blob:none https://github.com/leanprover/lean4 uses 203MB of space, which is not significantly larger than a single checkout.