feat(types): isoyear method

[kaijennissen]

• first steps for implementing iso_year method
• added isoyear method for duckdb

Description of changes

Added a new isoyear method for timestamps.

Issues closed

Resolved #8989

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[kaijennissen]

@cpcloud I'm not sure where the corresponding tests should be placed?

• Inside ibis/tests/expr/test_timestampy.py
  • as new parametrization of test_extract_fields
  • as a new test function, f.e. test_iso_year
• Inside ibis/backends/tests/test_temportal.py

[gforsyth]

Hey @kaijennissen!

For tests of ibis internals, like does the extract operation return the Ibis type we expect for a given input, those go in ibis/tests/expr.

For testing execution against backends (does the operation do what we want, which backends are implemented, etc), those go in ibis/backends/tests