Murisi/faster masp e2e1

[murisi]

Cut down the duration of the E2E tests by storing precomputed MASP transactions. A potential temporary fix while the MASP unit tests are being made. The advantages of this approach are as follows:

• The tests exercise the code in the MASP validity predicate
• The tests fully simulate (including full ZK-proofs) typical usage of the MASP client
• No changes to the client/stubs were required to enable it to be tested
• The acceptance of actual specific binary encodings of MASP transactions is tested

The disadvantages of this approach are as follows:

• The addresses of Albert, Bertha, and Christel must be fixed in e2e-tests-single-node.toml (as they occur in binary)
• The tests depend on a particular sequence of conversion tree states/anchors (i.e. 7 assets ...)
• If shielded transaction formats or reward function is changed, updating MASP tx data binaries is slow/cumbersome