import/get: inconsistent CRLF handling when importing git-tracked files in cross-platform projects

[pmrowla]

From #6049 (comment)

When we dvc import or dvc get a git-tracked file, DVC will read/download (and then track) the file with whatever line endings are in the git-committed blob. Depending on a user's git core.autocrlf config, the line endings in the blob may not match what git puts in the user's workspace.

Typically when working in a cross-platform project, users will set autocrlf=true so that git checks out files with \r\n line endings in their windows workspace, but commits blobs with unix \n line endings. If you dvc import one of these git-tracked files, the resulting DVC-tracked file will always contain \n endings (even on Windows).

This causes potentially unexpected behavior where the user will end up with an imported version of the file which contains line endings that are inconsistent with what they would get from git checkout

We should consider handing line ending normalization on checkout for imported git-tracked files, so that after dvc checkout, the files have line endings which are consistent with git checkout