Fix incorrect col calculate for pair.line_col method, and add integration test for cover it.

[huacnlee]

Hi @tomtau, when I use the new pair.line_col method in my project.

I found that col value is not correct:

https://github.com/pest-parser/pest/actions/runs/3899423161/jobs/6659084167

So I try to fix it, and add a complex integration test for cover it.

[tomtau]

Would it be possible to leverage the original line-col function (to give it an extra argument)?

[NoahTheDuke]

The code itself looks solid. I'm a little confused by why this change is needed. I think I just don't quite understand how the lines and cols are determined. Why do we need to start at 1,1 sometimes and 0,0 other times?

[huacnlee]

@NoahTheDuke In Pairs#move_cursor, it calculates the (line, col) position by uses a part of string by keep accumulating.

So it call Position#line_col just need get a number of offset of that str need to move (This is not like line, col. line, col is start from 1,1 buf offset need start with 0,0).

Here is a test fail result, before I change:

https://github.com/pest-parser/pest/actions/runs/3899423161/jobs/6659084167

[NoahTheDuke]

Cool, thanks.