feat: add strftime

[universalmind303]

Changes Made

• adds to_string/strftime.

Note for reviewers.

on the python side I added both to_string and strftime, but on sql I only added strftime.

The reasoning is that because we don't yet have namespaced prefixes on sql, so to_string is pretty generic, but on python it's dt.to_string which fits with our str.to_date and str.to_datetime.

Related Issues

closes #4094

Checklist

• Documented in API Docs (if applicable)
• [n/a] Documented in User Guide (if applicable)
• [n/a] If adding a new documentation page, doc is added to docs/mkdocs.yml navigation
• [n/a] Documentation builds and is formatted properly (tag @/ccmao1130 for docs review)

[codecov]

Codecov Report

Attention: Patch coverage is 69.66292% with 27 lines in your changes missing coverage. Please review.

Project coverage is 78.38%. Comparing base (60a3710) to head (0080ae6).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/daft-functions/src/temporal/mod.rs	69.23%	12 Missing ⚠️
src/daft-sql/src/modules/temporal.rs	62.96%	10 Missing ⚠️
src/daft-core/src/series/ops/time.rs	63.63%	4 Missing ⚠️
src/daft-functions/src/python/temporal.rs	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4146      +/-   ##
==========================================
- Coverage   78.38%   78.38%   -0.01%     
==========================================
  Files         796      796              
  Lines      103621   103710      +89     
==========================================
+ Hits        81226    81288      +62     
- Misses      22395    22422      +27     

Files with missing lines	Coverage Δ
daft/expressions/expressions.py	93.89% <100.00%> (+0.01%)	⬆️
daft/series.py	89.46% <100.00%> (+0.02%)	⬆️
src/daft-core/src/array/ops/time.rs	87.44% <ø> (ø)
src/daft-core/src/python/series.rs	93.57% <100.00%> (+0.02%)	⬆️
src/daft-functions/src/python/mod.rs	100.00% <100.00%> (ø)
src/daft-functions/src/python/temporal.rs	91.66% <75.00%> (-8.34%)	⬇️
src/daft-core/src/series/ops/time.rs	66.34% <63.63%> (-0.16%)	⬇️
src/daft-sql/src/modules/temporal.rs	81.90% <62.96%> (-6.56%)	⬇️
src/daft-functions/src/temporal/mod.rs	66.47% <69.23%> (+0.78%)	⬆️

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