Add extra class param for tblist function

[galachad]

Hey @krystian8207 please take a look, I didn't have any better idea for parameter name extra_class

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 66.48%. Comparing base (b974749) to head (b3216d1).

Files with missing lines	Patch %	Lines
R/source_tblist.R	33.33%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##              dev      #76   +/-   ##
=======================================
  Coverage   66.48%   66.48%           
=======================================
  Files          11       11           
  Lines        1966     1966           
=======================================
  Hits         1307     1307           
  Misses        659      659           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.