[BUG] Support union and structured data set types in flytectl

[pmahindrakar-oss]

Describe the bug

Currently flytectl doesn't support creating /extracting union types and hence is not able to creation executions for tasks which utilize these types.

Add support for these in the following files and consume the updated idl in flytectl
https://github.com/flyteorg/flyteidl/blob/master/clients/go/coreutils/literals.go
https://github.com/flyteorg/flyteidl/blob/master/clients/go/coreutils/extract_literal.go

And test it by creating an execution which involves these types from flytectl

Expected behavior

flytectl should be able to launch executions involving tasks with union and structured data set

Additional context to reproduce

No response

Screenshots

No response

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes