Allow to pass multiple lists of column coordinates

[markojaadam]

In case if we pass multiple areas it's a very reasonable use case to be able to pass column separators for each area. Tabula-java supports it natively and it works with submitting repeated column lists as java-native options. Additionally, it matches the order with the order of the areas.
It would be nice to have this feature wrapped into tabula-py.

[chezou]

Thanks for your contribution!

Overall looks good. Can you add unit tests for it?

[chezou]

Great! I didn't know multiple areas can be passed.

https://github.com/tabulapdf/tabula-java/blob/2cdf3b4fd3f7e921dca8cc6814cdd9316be40f0f/src/test/java/technology/tabula/TestCommandLineApp.java#L158-L160

[markojaadam]

@chezou I was doing a bit deeper research. What was misleading me when I initially tested this mode of working that I was testing it with 2 areas with the same number but different width of columns and it worked perfectly, it parsed both tables correctly and I was happy. However, after I started to generate multiple test PDFs and ran my PR against them I noticed that it forces the same column number on all of them with producing filler columns with empty text and all-zero-coordinates. After some additional test I've confirmed that means despite the java engine allows repeated column arguments, it actually ignores the subsequent set of coordinates and falls back to auto-detecting column separators. Also, after some search I've found this: tabulapdf/tabula-java#401. So sadly they officially don't support this, it was just unclean how does it work when we have multiple areas defined along with passing separator coordinates with --column. Sadly, for this reason I'm slocing my PR because this isn't an existing tabula-java feature.