Use PROPOSALS constant in models

[whoabuddy]

If a model doesn't accept a name as an input, it should use the value in the PROPOSALS constant.

This ensures that the value only needs to be updated in Clarinet.toml and utils/common.ts.

See CCIP-017 code as an example:

protocol/models/proposals/ccip017-extend-direct-execute-sunset-period.model.ts

Lines 15 to 19 in e7ee0d5

	export class CCIP017ExtendDirectExecuteSunsetPeriod {
	name = PROPOSALS.CCIP_017;
	static readonly ErrCode = ErrCode;
	chain: Chain;
	deployer: Account;