Specification of UTXOs/sats for batch inscribing

[RobertClarke]

Example: I hold 2 546 sat UTXOs in my ord wallet containing uncommon sats on the first sat in the UTXOs. I want to inscribe on both of them with one TX using batch. Example structure:

mode: separate-outputs
postage: 546
inscriptions:

• file: ~/example_image1.svg
  sat: d9447cf306398bd527de6f79fac7c7024dd1dc1c6643276f94417a43546a4c06:0:0:0
  destination: bc1p94xvz237p6l3cdx7xlkwvnz7pjkm2qvd2xwtzjcad7c5e48lll0sj2urha
• file: ~/example_image2.svg
  sat: e477ef67f9197d68cbd0032432bb6c36569a0afbcb5bc625b1e233fe2707dc2f:0:0:0
  destination: bc1p94xvz237p6l3cdx7xlkwvnz7pjkm2qvd2xwtzjcad7c5e48lll0sj2urha

[RobertClarke]

I'm personally adding a bounty of 20 uncommons for the first working PR that fits within the scope of this issue.

[raphjaph]

@RobertClarke have a look at #3115