Add compressed transaction format

[adlerjohn]

First stab at a compressed transaction format. Still outstanding for future PRs:

• Some sort of varint encoding to compressed various integer values
• Fixing how colors are indexed. We need to align both an on-Fuel color (32 bytes, pointing to the TXO that generated the token contract), and on-Ethereum (20 bytes, from a token contract address)

The biggest features of this compressed format are:

• Using TXOPointer and AddressPointer instead of raw UTXO ID and address (32 -> 7/6 bytes) (ref: Compressed Address Registries #111)
• Remove various fields entirely, as they're redundant