[FEA] Java Table concatenate should gracefully handle the single table degenerate case

**Is your feature request related to a problem? Please describe.**
When calling Table.concatenate with a single table, it throws an IllegalArgumentException rather than simply returning a new table with the same columns as the single input table. This forces calling code to special-case this scenario to avoid a crash.

**Describe the solution you'd like**
Table.concatenate should handle a degenerate concatenate of a single table by returning a new table containing the same columns as the original input table (i.e.: zero-copy via refcount)

**Describe alternatives you've considered**
Leave it as-is, callers must each special-case this scenario to avoid a crash.