feat(duckdb): Add transpilation support for BIT_LENGTH

[fivetran-amrutabhimsenayachit]

BIT_LENGTH(TO_BINARY('A1B2', 'HEX')) transpiles to BIT_LENGTH(UNHEX('A1B2')) — UNHEX returns BLOB, but DuckDB's BIT_LENGTH does not accept BLOB.
Modified this to use the correct DuckDB equivalent - OCTET_LENGTH(UNHEX('A1B2')) * 8.

 python3 -c "
from sqlglot import parse_one
from sqlglot.optimizer.annotate_types import annotate_types

sql = \"SELECT BIT_LENGTH('abc') AS short_str, BIT_LENGTH('hello world') AS long_str, BIT_LENGTH('') AS empty_str, BIT_LENGTH(NULL) AS null_str, BIT_LENGTH(TO_BINARY('A1B2', 'HEX')) AS bin_input\"
print(annotate_types(parse_one(sql, dialect='snowflake'), dialect='snowflake').sql('duckdb'))
"
-->
SELECT BIT_LENGTH('abc') AS short_str, BIT_LENGTH('hello world') AS long_str, BIT_LENGTH('') AS empty_str, BIT_LENGTH(NULL) AS null_str, CASE TYPEOF(UNHEX('A1B2')) WHEN 'BLOB' THEN OCTET_LENGTH(CAST(UNHEX('A1B2') AS BLOB)) * 8 ELSE BIT_LENGTH(CAST(UNHEX('A1B2') AS TEXT)) END AS bin_input

│ short_str │ long_str │ empty_str │ null_str │ bin_input │
│   int64   │  int64   │   int64   │  int64   │   int64   │
├───────────┼──────────┼───────────┼──────────┼───────────┤
│        24 │       88 │         0 │     NULL │        16 │

[github-actions]

SQLGlot Integration Test Results

Comparing:

• this branch (sqlglot:RD-1147695-bit-length, sqlglot version: RD-1147695-bit-length)
• baseline (main, sqlglot version: 0.0.1.dev1)

By Dialect

dialect	main	sqlglot:RD-1147695-bit-length	transitions	links
bigquery -> bigquery	23872/23877 passed (100.0%)	21252/21252 passed (100.0%)	No change	full result / delta
bigquery -> duckdb	2105/2624 passed (80.2%)	0/0 passed (0.0%)	No change	full result / delta
snowflake -> duckdb	1511/2674 passed (56.5%)	0/0 passed (0.0%)	No change	full result / delta
snowflake -> snowflake	65910/65910 passed (100.0%)	63015/63015 passed (100.0%)	No change	full result / delta
databricks -> databricks	1364/1364 passed (100.0%)	1364/1364 passed (100.0%)	No change	full result / delta
postgres -> postgres	6040/6040 passed (100.0%)	6040/6040 passed (100.0%)	No change	full result / delta
redshift -> redshift	7059/7059 passed (100.0%)	7059/7059 passed (100.0%)	No change	full result / delta

Overall

main: 109548 total, 107861 passed (pass rate: 98.5%), sqlglot version: 0.0.1.dev1

sqlglot:RD-1147695-bit-length: 102733 total, 102733 passed (pass rate: 100.0%), sqlglot version: RD-1147695-bit-length

Transitions:
No change

✅ 1 test(s) passed

[georgesittas]

@fivetran-amrutabhimsenayachit check out the latest changes I made.