Allow Features in Implicit Accounts

[PhilippGackstatter]

Description of change

Allow features in implicit accounts because they allow for more seamless implicit account creation. The more permutations of Basic Outputs we allow implicit account creation addresses in, the more seamless implicit account creation becomes.

On the other hand, Storage Deposit Return, Timelock and Expiration Unlock Condition are not useful for implicit account creation, so they continue to be disallowed.

• Storage Deposit Return UC: Having to return the funds on an implicit account to the sender means the full account we want to transition to must be funded by other means. In a typical onboarding scenario these funds do not exist, so SDRUC would only make it more complicated to create the full account.
• Timelock: Would be harmless, but timelocks are not permitted on full accounts either. It would be odd to be able to use the implicit account to issue blocks (because the accounts ledger does not respect the timelock) but not be able to do the implicit account conversion until the timelock expires.
• Expiration: Necessarily, the the Return Address would not be an implicit account creation address, but probably a regualr Ed25519 Address. Then for the Address the Basic Output would be an implicit account, but for the Return Address it would be a regular output, which is very undesirable behavior.

How the change has been tested

Added new tests for where implicit account creation addresses are allowed.