[Feature] Allows DryRun

[johandry]

Is your feature request related to a problem? Please describe.
Allows the option to do a DryRun

Describe the solution you'd like
Option 1: c.DryRun(true).Apply() then c.DryRun(false)
Option 2: c.Apply(..., opt) where opt.DryRun = true

Describe alternatives you've considered
So far the DryRun have not been considered.

Proposal
Create an attribute of the client named DryRun. For every modification method (Apply, Create, Delete, Replace) if the client has the DryRun attribute set to true, the helper should call DryRun(true). Example:

helper := resource.NewHelper(info.Client, info.Mapping)
if c.DryRun {
  helper = helper.DryRun(true)
}

Additional context
This may be an option to validate if the resources to visit are valid to apply, delete, create or replace. Optionally, it may be an option to get YAML or JSON representation of a resource.

References
None