[Revive]: Reassess the restriction blocking Root origin from creating contracts

[sphamjoli]

Context

pallet-revive's exec stack currently blocks Origin::Root from instantiating
contracts:

if entry_point == ExportedFunction::Constructor {
    // Root origin can't be used to instantiate a contract.
    ensure!(matches!(self.origin, Origin::Signed(_)), DispatchError::RootNotAllowed);
    ...
}

This forbids any call path that enters revive under bare_call(RuntimeOrigin::root(), ...)
from reaching a CREATE opcode, even when the inner contract semantically wants to
deploy a sub-contrac.

[sphamjoli]

@andrew-ifrita @athei

for more context see

TRACE runtime::revive: frame finished with: Err(ExecError {
    error: RootNotAllowed,
    origin: Caller
})
DEBUG runtime::revive: Create failed: ExecError { error: RootNotAllowed, origin: Caller }
TRACE runtime::revive: frame finished with: Ok(ExecReturnValue { flags: REVERT, data: [] })
TRACE runtime::revive: frame finished with: Ok(ExecReturnValue { flags: REVERT, data: [] })
...
Bare call ends: weight_consumed=Weight { ref_time: 8.4 G, proof_size: 494 KiB }
WARN runtime::indiv-pallet-dotns-gateway: unknown contract revert selector; data = []

[sphamjoli]

This is our suggested mainnet solution somehow allow Root to create contracts, for W3S we will use the current implementation

[athei]

We can probably just remove the check. It was there because the origin pays the ED to create the new contract's account. With root there was nobody to pay. AFAIK we are minting the ED now since the PGAS PR.

We should

• Remove the check
• Mint the ED for the new contract in case that is not already the case.

[xermicus]

Likely the early bail is there because origin has no address so its unclear what to use.

[athei]

Likely the early bail is there because origin has no address so its unclear what to use.

Root will still not be able to instantiate a contract for that reason. This simply allows the origin to be root as long as another contract is in between to act as instantiator. Allowing root to instantiate would require setting an address for it. Which is not what we are doing right now. This could be done later.

[xermicus]

If that guard is redundant for this case I also don't see any obvious reason for it.

[athei]

It is probably a leftover. AFAIK it should no longer be needed: We skip deposits if root origin. ED was the blocker to allow it.