Add keys into object print methods

[nikolas-burkoff]

From insightsengineering/teal#435 - added into backlog as new feature

For Datasets, Connectors and TealData would be great to output the keys in the print statement (maybe including joinkeys for TealData with an optional argument to print ?)

[pawelru]

If we are about to add keys then I would also include parent dataname

[gogonzo]

please include other relevant attributes of the class object.

• dataname
• parent dataname
• keys
• etc