Support "generative" and "long-form" engines under "BotLocales.VoiceSettings" of the AWS::Lex::Bot resource in CFN

### Name of the resource

AWS::Lex::Bot

### Resource name

_No response_

### Description

Lex V2 API supports 4 engine types in BotLocale VoiceSettings:

https://docs.aws.amazon.com/lexv2/latest/APIReference/API_VoiceSettings.html

However, the corresponding CloudFormation resource: "AWS::Lex::Bot" currently supports only 2 engine types: "standard" and "neural":

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-lex-bot-voicesettings.html

This request is to support the remaining two engine types, namely: "long-form" and "generative" under BotLocale VoiceSettings of the CloudFormation "AWS::Lex::Bot" resource.

### Other Details

_No response_

Start by comparing the AWS::Lex::Bot VoiceSettings documentation with the linked Lex V2 VoiceSettings API reference. Locate the CloudFormation resource definition and its validation or coverage tests; done means the long-form and generative engine types are accepted under BotLocale VoiceSettings.

Written by the indexing model from the issue text.