go-bs-lmdb can't be built due to undefined blockstore.ErrNotFound functions called

[fbac]

go-bs-lmdb can't be built due to undefined blockstore.ErrNotFound functions called:

# github.com/filecoin-project/go-bs-lmdb
../../../go/pkg/mod/github.com/filecoin-project/go-bs-lmdb@v1.0.6-0.20211215050109-9e2b984c988e/blockstore.go:342:20: undefined: blockstore.ErrNotFound
../../../go/pkg/mod/github.com/filecoin-project/go-bs-lmdb@v1.0.6-0.20211215050109-9e2b984c988e/blockstore.go:369:20: undefined: blockstore.ErrNotFound
../../../go/pkg/mod/github.com/filecoin-project/go-bs-lmdb@v1.0.6-0.20211215050109-9e2b984c988e/blockstore.go:397:20: undefined: blockstore.ErrNotFound

Additional context
blockstore changed its way to raise ErrNotFound since this PR, which breaks compatibility.

The logic should be changed to use ipld.ErrNotFound instead of blockstore.ErrNotFound.