Please treat 1D table objects as vectors

[gusl]

Is your feature request related to a problem? Please describe.
Sometimes one of the inputs is a table of bucketed counts, which should clearly be treated as a numeric vector, but cmdstanr can't handle it.

Describe the solution you'd like
Automatically call as.numeric() if it's a 1D table.
For 2D tables, maybe automatically call as.matrix().

Describe alternatives you've considered
Alternative: give a clear error message about needing to convert the table to numeric. The "asJSON" part is distracting and obscures what needs to happen.

Additional context
Add any other context about the feature request here.

[jgabry]

Thanks for opening the issue @gusl. @rok-cesnovar I can implement this. Do you prefer automatically converting tables or an informative error message? Either is fine by me.

[rok-cesnovar]

I think converting should be simple? I would go with that first if possible.

[jgabry]

Yeah it's pretty simple, although there's a little bit of R weirdness here. In the case of 2-D tables we can't use as.matrix because that preserves the "table" class (as.matrix(table) is still a table for some reason) and we can't use as.array for 3-D tables for the same reason. So I think we need to remove the table class with unclass(table) instead of calling functions like as.matrix. Opening a PR now.