Remove support for reading older file versions

[maxnoe]

Please describe the use case that requires this feature.
With the planned and already merged changes to the data model (#1923, #1949, #1899, #1426, #1591 and some others) I think we are at the point where we should remove a number of workarounds and compatibility layers to simplify the code.

Describe the solution you'd like

Drop support for all but the current version of the data model to simplify the code.

Describe alternatives you've considered

Keep maintaining these workarounds and compatibility layers. I don't think we should do this, especially not for 1.0.

[kosack]

Yes, I think this is ok . we are still in a pre 1.0 release, so shouldn't worry too much about backward compatibility

[maxnoe]

This for me would also include removing the support for calculating hillas parameters in CameraFrame. It will improve performance (because the unit checks will not be necessary) and also pave the way for applying pointing corrections in the transform from CameraFrame to TelescopeFrame before calculating hillas parameters.

Thoughts?