Don't create the sealed file in precommit1

[magik6k]

Today precommit1 just copies unsealed bytes to the 'sealed' file, and does nothing else with them ->

rust-fil-proofs/filecoin-proofs/src/api/seal.rs

Lines 91 to 98 in 128f720

	// Copy unsealed data to output location, where it will be sealed in place.
	fs::copy(&in_path, &out_path).with_context(|| {
	format!(
	"could not copy in_path={:?} to out_path={:?}",
	in_path.as_ref().display(),
	out_path.as_ref().display()
	)
	})?;

This leads to confusion, and redundant work on lotus side as it needs to manage that file between PC1/2.

Ideally Precommit1 would either not create the sealed file at all - that would happen in early PC2, or the sealed file would actually contain the correct, sealed data (in which case PC2 could possibly not require unsealed data access?)

[vmx]

This issue is about bundling to many things in the single precommit1 call. Those things have been split and are available through the FFI PR at filecoin-project/filecoin-ffi#402.