feat(python): Warn on inefficient use of map_elements for additional string functions

[alexander-beedie]

Ref: #9968.

The BytecodeParser can now also detect/translate Python string ops such as...

• s.strip()
• s.lstrip()
• s.rstrip()
• s.endswith('x')
• s.endswith(('x','y'))
• s.startswith('x')
• s.startswith(('x','y'))

Note that as we don't (currently ;) support multiple strings being passed in to starts_with and ends_with, such expressions are translated to a suitable contains regex instead.

Example

import polars as pl

df = pl.DataFrame({"s":["xxyx","123xx", "45yx?"]})
df.with_columns(
    match = pl.col("s").map_elements(lambda s: s.endswith(("?", "!"))),
)

# PolarsInefficientMapWarning: 
# Expr.map_elements is significantly slower than the native expressions API.
# Only use if you absolutely CANNOT implement your logic otherwise.
# Replace this expression...
#   - pl.col("s").map_elements(lambda s: ...)
# with this one instead:
#   + pl.col("s").str.contains(r'(\?|!)$')
```

[codecov]

Codecov Report

Attention: 18 lines in your changes are missing coverage. Please review.

Comparison is base (815732b) 80.76% compared to head (66fd1a1) 77.95%.
Report is 5 commits behind head on main.

Files	Patch %	Lines
py-polars/polars/utils/udfs.py	20.00%	15 Missing and 1 partial ⚠️
py-polars/polars/utils/various.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14565      +/-   ##
==========================================
- Coverage   80.76%   77.95%   -2.81%     
==========================================
  Files        1326     1326              
  Lines      173035   173058      +23     
  Branches     2439     2446       +7     
==========================================
- Hits       139758   134916    -4842     
- Misses      32805    37698    +4893     
+ Partials      472      444      -28     

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[stinodego]

Looks good to me, thanks!