[DOCS] Add documentation for read_iceberg

[jaychia]

1. Add docstring
2. Add API docs
3. Adds a new section in user_guide/integrations for data_catalogs

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (fd662c1) 84.76% compared to head (c995b1a) 84.69%.

❗ Current head c995b1a differs from pull request most recent head 3130602. Consider uploading reports for the commit 3130602 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1769      +/-   ##
==========================================
- Coverage   84.76%   84.69%   -0.08%     
==========================================
  Files          55       55              
  Lines        5554     5554              
==========================================
- Hits         4708     4704       -4     
- Misses        846      850       +4     

Files	Coverage Δ
daft/io/_iceberg.py	21.27% <ø> (ø)

... and 2 files with indirect coverage changes