Add getParamInfo-method to Driver
Add getParamInfo-method to Driver

The driver class has a method-pair getParam/setParam, this commit adds
a getParamInfo-method which is complementary to setParamInfo. It is
useful for cases where information about these additional PV-properties
changes at runtime and needs to be queried.

paulscherrerinstitute/pcaspy,paulscherrerinstitute/pcaspy,paulscherrerinstitute/pcaspy