fix(node): harden transaction inclusion logic to account for fee market

[raulk]

This PR improves correctness of tx inclusion logic on two fronts.

1. Begins rejecting messages with invalid limits at CheckTx time:
   • Gas fee cap below minimal base fee.
   • Gas limit above maximum block gas limit.

Some type shenanigans via downcasts were necessary to deal with #1241. Tested by extending a materializer test.

2. Exclude non-includable messages at proposal time.

   • I removed the MessagesSelector trait because it was unusable. The vector holding selectors cannot used boxed objects because the trait is not object-safe as it has methods with generic parameters. Also, there's no point over-engineering this prematurely.
   • Also removed the decreasing sorting by gas limit; we prefer to randomize for security (otherwise an attacker could drip brutally overestimated transactions just below the block gas limit to DoS the chain).

3. Randomize message selection to prevent attackers from predicting or controlling message inclusion.

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This change is