refactor `TransactionBuilder`

[hal3e]

Currently, the transaction builders need a provider when building transaction and the build method is async.
We should refactor the transaction builders and try to make the build method sync. The estimation or assemble should happen separately and build should finalize the tx and sign it. We could explore the api and expose ways to manually set required fields or estimate them using the node.

[netrome]

Note that this is a pretty substantial refactor, but it makes a lot of sense to support constructing transactions without redundant node interactions.