Feature: Allow for specifying IDs via the API

### Feature description

The examples in the swagger UI suggest that we can specify an ID when we Create/Post a new Pipeline/Connector/Processor. eg.


However, the underlying API and orchestrators don't seem to actually allow for doing so - it just [sets a new UUID](https://github.com/ConduitIO/conduit/blob/42bee9658264429b03f27af347e98f3bde05cb7d/pkg/orchestrator/pipelines.go#L47).

## Proposal

It would be helpful if the API and orchestrators could accept an optional ID field. If it exists, use it. If not, create a UUID.

This would both align it with the yaml config file behaviour, as well as make it vastly easier to deal with configurations since we can know exactly what the IDs are/should be rather than needing to List them all, parse the response, extract the assigned (UU)IDs, then use them.

Most importantly, for me, it would allow for aligning the ID with specific variables in the broader system - eg a server or client number.