Add the ability to extract and check tables in pdf files

[VitalyShalaev]

Many pdf files contain tables, but the pdf-test only extracts text from pages. I would like to check the contents of the tables in a more convenient way.

[asolntsev]

@VitalyShalaev Thank you for the suggestion. How exactly do you want to find the tables?

[VitalyShalaev]

@asolntsev
So far there are 2 options:

1. Automatic detection on the page and output of the result in the form of a list of lists.
2. Definition of the table by the specified column names.

[VitalyShalaev]

@asolntsev
For case 1:
Found the SpreadsheetExtractionAlgorithm at https://mvnrepository.com/artifact/technology.tabula/tabula/1.0.4.
But there are some problems with defining the text in the cells of some tables, trying to determine the reason, but not sure if I can do it.

[VitalyShalaev]

@asolntsev
For case 1:
I found a library that works well https://mvnrepository.com/artifact/e-iceblue/spire.pdf/10.1.3
Example: https://medium.com/@alice.yang_10652/extract-table-data-from-pdf-in-java-8dc4fad73752