Pyclient: add filename/path to export method and add possibility to return exported data in memory

[YpeZ]

Is your feature request related to a problem? Please describe.
When exporting data using the export method, the data is saved by the name of the table or schema in the working directory of the user. This is sometimes unwanted as user may be working on, for example the same table from different schemas where the export of one would overwrite the other on the disk. Often, a different directory than the working directory for saving the data is preferable. Additionally, users might only need the data to be in memory and not saved on the disk at all.

Describe the solution you'd like

• Add the option to specify the path and filename for the export
• Let the method return the exported data
• Add the option to not save the data on the disk