Remove support for custom (enum) type overrides

[mbj]

This is a good feature to have. And I'd love to bring it back in a more maintainable setting. But for now it has to go to spend my limited time budget on higher ROI tasks.

The full story:

The cloud formation specification has many String fields where the values are not free text but only certain values are valid.

Valid values are not exposed in the cloud formation spec, and are only available in the documentation rich text.

For this reason stratosphere used to ship a manual maintained set of overwrites that would map resource properties to manually defined enum-a-like types.

This manually maintained set of enum types often goes stale and leads to issues where AWS would release a new supported value and the stratosphere library was not yet updated to support that new value - as a simple regeneration from the spec is not enough to catch these.

This feature can be brought back with this thoughts in mind:

• We may be able to parse the enum values from parsing the documentation string.
• If we bring it back each enum type needs to have a "custom" type member so library users always have an escape hatch for stratosphere lagging behind AWS.