Simplify CostModel internals

[JaredCorduan]

The CostModel type contains a Map Text Integer named cmMap:

https://github.com/input-output-hk/cardano-ledger/blob/3f5123c3ae009ec1ac2779410da6604a236e67f2/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/Scripts.hs#L231-L235

Change the type of cm to be [Integer].

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Context for those curious

This map cmMap is only used by the ledger to create a Plutus evaluation context (of type EvaluationContext), and it is only stored in the ledger so that we can serialize it (deserializing it allows us to construct the EvaluationContext again).

The newest version of Plutus now follows this plan, and hence only needs [Integer] to be constructed (ie no longer a Map Text Integer).

Moreover, there is no longer any need to use the Text keys in the ledger. So costModelParamsNames and costModelParamsNamesSet can be deleted as a part of this change. (introduced here https://github.com/input-output-hk/cardano-ledger/pull/2992/files#diff-f481d9eb9f793235d9fc4a1965ec1e0a01bed313f90adb11dcd9aa099a4cd738R320-R326)