Add a --no-symlink option for the save command

[merulus]

I just accidentally deleted a script.

I did something like echo 'hello' | save -f script.nu,
where script.nu is symlink to another_script.nu.

Now, the another_script.nu got accidentally overwritten.

In order to safely overwrite a file, I have to:

if ('script.nu' | path exists) { rm 'script.nu' }
echo 'hello' | save script.nu

which makes the -f, --force option less useful.

I think it would be better to not follow symlinks by default.
To follow symlinks, we could write save -f ('script.nu' | path expand).

Otherwise, just add a --no-symlink option to the save command would be fine.