Fix relative links extraction

[yxzhu16]

GitHub issue(s): #501

What does this Pull Request do?

• Set baseUri to be src instead of base when extracting links, and deleted base parameter The issue occurred because relative links cannot be extracted by link.attr("abs:href") when baseUri is not set. As I look through the code, param base is never provided anywhere when ExtractLinks is called, so default value "" is always used, and baseUri is never set. However, baseUri is required to be able to extract relative links.

Instead of adapting the Python UDF to include the base parameter, I think it makes sense to set the baseUri to be src. Similar as https://github.com/archivesunleashed/aut/blob/00e816629a86d767ff9c11324963d2c8368b0a35/src/main/scala/io/archivesunleashed/matchbox/ExtractImageLinks.scala#L42

I tested on Wayback Machine bbc pidgin pages and it works.

• Updated tests One concern is that after modification the number of relative links is really really large compared to before, eg. in one of the test cases the number of links extracted 600 -> 30k. And in ArcTest "Count links RDD" I encountered java.lang.StackOverflowError because of the large number of links.

How should this be tested?

1. Load the example warc and extract links
2. Filter the src domain to be "deadlists.com"
3. Lines highlighted should show up where dest are relative links in the source html

[codecov[bot]]

Codecov Report

Merging #504 into main will decrease coverage by 0.02%. The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main     #504      +/-   ##
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- Coverage     88.85%   88.83%   -0.03%     
  Complexity       57       57              
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  Files            43       43              
  Lines          1014     1012       -2     
  Branches         86       85       -1     
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- Hits            901      899       -2     
  Misses           74       74              
  Partials         39       39