feat(PECOBLR-1766): Python UDF Support

[sd-db]

Description

Users want to create Python UDFs using dbt's functions feature on Databricks, but the current dbt-databricks adapter restricts UDF creation to SQL only. This PR looks to add support for Python UDFs (of the following form/format + more)

# def + explicit call -- for more complex logic
def compute(value):
    return value * 2
return compute(value)

# Inline return -- parameters are available as local variables
return value * 2

Checklist

• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have updated the CHANGELOG.md and added information about my change to the "dbt-databricks next" section.

[github-actions]

Coverage report

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File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
dbt/adapters/databricks
relation.py
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[benc-db]

Approve with minor test style comments