Support cancellation tokens in FastReport.Prepare

[Max]

Is your feature request related to a problem? Please describe.
Sometimes background report generation needs to be cancelled, for example, when SQL is slow.

Describe the solution you'd like
I would like to pass CancellationToken to FastReport.Prepare. It would be a non-breaking change if you default the parameter to CancellationToken.None.

Describe alternatives you've considered
I see that there's an Abort method but the docs don't have any examples on how to properly use it or if it's thread safe.
I suspect that Abort only cancels the report generation but not the DB query.

[Δ]

Hello, what about PrepareAsync? It has a CancellationToken in params

[Max]

This method is in the sources but not in the nuget package.

[Max]

@Alekarfes could you please add a link to the commit which resolves this?