Can we add fallback behaviour for automatically pre-fixed namespace datasets?

[ankatiyar]

Description

Following discussion #4506

Currently a namespaced pipeline also expects the inputs, outputs and parameters to be namespaced. Users can either:

• Add namespaced datasets/parameters to configuration
• Specify mappings of inputs and outputs in the pipeline() function

The goal for this ticket is to explore if this behaviour can be updated so:

• The input, output, parameter mapping can be automatic (eg. use the non-namespaced entry if the namespaced dataset is not available)
• This behaviour is clear and unambiguous

Context

#4506 (comment)