Bip54: add sequence, timestamp (and version) to GBT

The discussion revolves around the consensus fixes introduced by BIP54, which are currently not contentious within the community. However, there is a concern raised about the proposal to include new additions to the getblocktemplate within BIP54. It is argued that these additions could potentially complicate matters by expanding the policy surface unnecessarily. The suggestion made is that these new additions should be specified in a separate document or proposal, where they can be appropriately addressed and discussed without interfering with the consensus fixes of BIP54. This approach would help in maintaining the focus on the uncontroversial aspects of BIP54 while allowing for a dedicated discussion on the new getblocktemplate additions and their implications.