[redknot] unspecified-encoding lint rule

[plredmond]

Implement an unspecified_encoding.py lint rule like the one in #11288.

import tempfile

tempfile.TemporaryFile("w")  # error

tempfile.TemporaryFile("w", encoding="utf-8")  # ok

This is still a draft.

[github-actions[bot]]

ruff-ecosystem results

Linter (stable)

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