Use res2df instead of ecl2df

[yngve-sk]

Hello from SCOUT, this is relating to the rename of ecl2df to res2df, I think this covers most of it but please double check it if something seems to be missing.

[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (2142fc5) 86.14% compared to head (70e2c01) 85.38%.

❗ Current head 70e2c01 differs from pull request most recent head e83ae6f. Consider uploading reports for the commit e83ae6f to get more accurate results

Files	Patch %	Lines
src/subscript/check_swatinit/check_swatinit.py	84.61%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #637      +/-   ##
==========================================
- Coverage   86.14%   85.38%   -0.77%     
==========================================
  Files          49       49              
  Lines        7054     7054              
==========================================
- Hits         6077     6023      -54     
- Misses        977     1031      +54     

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