Updates for ModelParametersSingletonPkg

[JimLewis]

ModelParametersPkg is has been extended to a singleton in ModelParametersSingletonPkg. Both are referenced in OsvvmCommonContext.

If you are willing to, please update the shared variable in VideoBusTx.vhd:
shared variable Params : ModelParametersPType;
to:
signal Params : ModelParametersIDType ;

Also update all uses of it as a PT to uses as a singleton.

An example of this is in OsvvmLibraries/AXI4/Axi4/AxiManager.vhd. Note that the params has been put into the record. Internally in the Axi4Manager it could of taken advantage of this and not created the signal Params. I have not updated the subprograms that send the settings to the VC, however, one thing that can be done is to set Params directly in the subprograms rather than passing it through the record and then setting it in the VC.

If you do this, please do a pull request against the OSVVM version of your library.

I don't think ModelParametersPkg will ever go away, I just prefer the OSVVM library VC to show preferred use cases. I am trying to weed uses of protected types out of the user space - as the calls are inconvenient and singletons give us additional advantages in many of the data structures.