refactor: to allow connector/flow steps to interchange behaviours in the flow

[keevan]

• feat: fill in name of new steps based on step type
• [wip] feat: flow and connector steps can now be used interchangably
• wip: add curl step with dual step support
• wip: adjust curl step, add helper methods to ease authoring
• wip: flip the check in the connector engine step because iterator-esque steps no longer return true. Instead they should explicitly return false when things go bad.
• everybody needs variables, even connectors
• the magic: if the step type is resolved to a flow, then it is a flow step, otherwise it is a connector step.
• refactor: simplify generate_engine_step methods for flow/connector steps
• add connector flag in steps table, update dot graph handling to visually display this change and fix side effect flags
• fix: step chooser / new step form (side quest)
• For connector-like steps, the input isn't real and so should be an empty object.
• changed curl_step to curl, updated handling of prefilled names for new steps
• fix weird issue where has_side_effect wouldn't enter probably magic getters

Prooof of concept sprinkled with some cleanup along the way:

Example workflow:
new_dual_curl_step_20220806_0802.yml.txt

Related to #422