Fix TSApplicationGenerator to use Result<> instead of #{Result}

[drganjoo]

The earlier PR, which ensured that a Smithy shape named Result does not conflict with the Rust type Result, had a bug in TSApplicationGenerator. The rustTemplateBlock was using #{Result} but preludeScope was not passed in as a parameter.

This bug can be addressed in two ways:

1. Pass *RuntimeType.preludeScope to the rustBlockTemplate call
2. Remove #{Result} from rustBlockTemplate and continue using Result<>

This PR implements the second approach because:

1. TSApplicationGenerator is slated for deprecation
2. The CI step CI / PR Bot / Generate diff and upload to S3 (pull_request) currently fails when comparing codegen between HEAD and this version. Removing #{Result} is the most reliable way to avoid parameter-passing issues with rustBlockTemplate