Check if stake addresses in proposals are registered onchain

[CarlosLopezDeLara]

Changelog

- description: |
    `transaction build` now checks and fails if stake addresses used for deposit return or treasury withdrawals in proposals are NOT registered on-chain. 
# uncomment types applicable to the change:
  type:
   - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

Resolves #900

How to trust this PR

Tested locally with a Treasury Withdrawal action where neither the deposit return or funds receiving stake addresses are registered:

cardano-cli conway governance action create-treasury-withdrawal \
--testnet --governance-action-deposit 100000000000 -\
-deposit-return-stake-verification-key-file example/utxo-keys/stake4.vkey \
--anchor-url https://tinyurl.com/3wrwb2as \
--anchor-data-hash 52e69500a92d80f2126c836a4903dc582006709f004cf7a28ed648f732dff8d2 \
--funds-receiving-stake-verification-key-file example/utxo-keys/stake4.vkey \
--transfer 1000000000 \
--constitution-script-hash fa24fb305126805cf2164c161d852a0e7330cf988f1fe558cf7d4a64 \
--out-file example/transactions/treasury.action

cardano-cli conway transaction build \
--proposal-script-file ./guardrailscriptV2/guardrail-script.plutus \
--tx-in-collateral fe7c2bd546dbd9b8d07cb677877842538e8d8695f439460804edcc8dec48b4d6#1 \
--proposal-redeemer-value '{}' \
--tx-in fe7c2bd546dbd9b8d07cb677877842538e8d8695f439460804edcc8dec48b4d6#1 \
--change-address addr_test1qpxswhl4wqx9wz7a2xm22f8kykyltcm9vq7gdh6acjpav0nyf3wxwla9x63vwcdnehthn9queenth86fuhzyy5tv23wqjg8gqx \
--proposal-file example/transactions/treasury.action --out-file example/transactions/treasury-tx.raw

Command failed: transaction build  Error: Stake credential specified in the proposal is not registered on-chain: 
fromList [StakeCredentialByKey "baf951461969b293ae04813af76e15b451c2921bbde53580306d817c"]

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details.
• Self-reviewed the diff

[palas]

I haven't tested it, but code looks good to me 👍
I just wrote a suggestion.