take intersection of genes in the `get_single_cell_experiment` function

[stemangiola]

@myushen This is in reference to

https://teams.microsoft.com/l/message/19:130d71a5-dc95-495c-b678-77fe3c8131c5_2c56e6fb-516c-470d-8000-2e655cd72bbc@unq.gbl.spaces/1710302042265?context=%7B%22contextType%22%3A%22chat%22%7D

The solution is to

Change the get_SCE function, but NOT the import function.

Commit 1:

• Create a function that takes a list of SCE and tests (+ warning warning("CuratedAtlasQuery says ....") ) is the genes do not completely overlap
• Build the unit test for it

Commit 2:

• Create a function that takes a list of SCE, run the test (commit 1), select just overlapping genes and cbind those
• Build the unit test for it

Commit 3:

• Use the function of commit 2 in the API.