Support MessagePackEachRow import format

[altexy]

I offer in addition to JSONEachRow support the similar format, but using sequence of MessagePack map objects.

The existing MsgPack format is schema-less, just sequence of MessagePack encoded values.

BSONEachRow is great, but don't have full UInt64 support, because internally support only Int64.
At the moment only RowBinaryWithNames format supports widely used UInt64 type, I'm talking about row-oriented self-describing binary formats. But it has a different usage pattern, because it has a header and multiple rows.

I want to have a format like JSONEachRow which make possible to change the fields set on the fly, but binary.

IMO need to support input_format_skip_unknown_fields flag