[5.x] Only apply the published filter when not in preview mode

[TheBnl]

Possible fix for issue #6134

Checks if we're in isLivePreview before appending $filters['status'] = 'published';
Works similar as the fix made for the REST API #10229

[duncanmcclean]

Would you be able to add a test for this?

[TheBnl]

Sure, i'll setup a test for checking if draft entries are received with a token and omitted without a token. 👍

[TheBnl]

I've added the testcase. While running the test I also needed to fix a line where the filters would default to null when empty. This should actually default to an empty array, further down the line the array type is required. Because published was always filtered this was previously not an issue.