Improve missing strategy text in impute() #513
Description
A likely common mistake when specifying strategies for the impute function is for the user to put "J2R" instead of "JR". When this happens we currently display the following error:
Required strategy "J2R" has not been defined
The message as written is potentially ambiguous as it is not clear whether the user has made a typo or if they are expected to provide the strategy themselves, it also isn't that helpful as it doesn't specify what strategies are available.
I'd propose we adjust it simply to print out the list of available strategies coming from the strategy list object e.g.
> No implementation for strategy "J2R" is available. Available strategies include:
- JR
- CIR
...