Expand scope of BigDecimal testing.

[gregturn]

H2 apparently supports the table types backing BigDecimal to also return NaN, +Inf, and -Inf, all types unsupported natively by BigDecimal. We need expanded testing and verification of handling this in a cohesive fashion.

[katzyn]

REAL, DOUBLE PRECISION, FLOAT and DECFLOAT may have these special values in H2. FLOAT doesn't have an own implementation, it is mapped to REAL or DOUBLE PRECISION depending on declared scale. REAL values should normally be read and set as float or Float, DOUBLE PRECISION should normally be read and set as double or Double and they all support these values; so the only problematic type is DECFLOAT. It can be safely read as String, but people usually want to have a some numeric value. Therefore situation is complicated. BigDecimal doesn't support these special values, but it can hold all other values of DECFLOAT, unlike other numeric classes and primitive types from Java.