Summary of the new feature / enhancement

As a heavy user of dynamic parameters, I often find myself tripping over their basic failures in constructability.

Dynamic Parameters are needlessly difficult to construct.

The shortest possible constructor is:

[Management.Automation.RuntimeDefinedParameter]::new("A", [psobject], @())

and it fails in an entreatingly confusing way, informing me that I could not bind "A" to "AllParameterSets", without telling me why.

Dynamic Parameters should be easier to construct.

The need goes beyond simplifying existing implementation and fixing its buggier parts:

A very common scenario is exposing dynamic parameters from one command to another.

This should also be easier to construct

Proposed technical implementation details (optional)

• Add simplified constructors to [Management.Automation.RuntimeDefinedParameter]
  • Constructing from only a name should create a [PSObject] parameter that accepts ValueFromPipelineByPropertyName
  • Constructing from a name and a type should add an empty [Parameter()] attribute
• Allow [Management.Automation.RuntimeDefinedParameter] to be coerced from [Management.Automation.ParameterMetadata]
• Create extension methods to assist in custom conversion to [Management.Automation.RuntimeDefinedParameter]
• Enable adding dictionaries to [Management.Automation.RuntimeDefinedParameterDictionary]
• Adding type accelerators [DynamicParameter], [DynamicParameters], so that less typing is required to create them.