[UI Feature] Enum type support in Launch form

[kumare3]

Motivation: Why do you think this is important?
Related to #590
There is currently no way to launch a Workflow / Task that accepts an enum type as an input from the Flyteconsole.

Goal: What should the final outcome look like, ideally?
Users should be able to launch workflows / tasks that accept an Enum type. Enum type is a simple list of string values, with the first one being default. The UX can be a simple drop down

Example workflow in FlyteSnacks https://github.com/flyteorg/flytesnacks/blob/master/cookbook/core/type_system/enums.py

[Optional] Propose: Link/Inline OR Additional context AND/OR Mock ideas
A Simple dropdown list

[jsonporter]

Support for this feature has been merged to master and will be included in the next release.

flyteorg/flyteconsole#178