[FEAT] Partitioning exprs for Iceberg

[samster25]

Implements the following partitioning expressions that return the number of units since epoch time UTC.

• partitioning_days
• partitioning_hours
• partitioning_months
• partitioning_years

[codecov]

Codecov Report

Merging #1680 (af14473) into main (7d7938f) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1680      +/-   ##
==========================================
- Coverage   85.00%   84.98%   -0.03%     
==========================================
  Files          55       55              
  Lines        5329     5341      +12     
==========================================
+ Hits         4530     4539       +9     
- Misses        799      802       +3     

Files	Coverage Δ
daft/series.py	92.62% <100.00%> (+0.23%)	⬆️

... and 1 file with indirect coverage changes