feat(duckdb): UPPER() handles byte input

[toriwei]

BigQuery UPPER() supports VARCHAR -> VARCHAR AND BYTES -> BYTES
DuckDB upper() supports VARCHAR -> VARCHAR

To improve transpilation from BigQuery, this PR allows DuckDB to handle byte input by casting it to varchar and casting the upper expression to blob. Created helper method to handle casting logic, as this mirrors the work done for LOWER transpilation #6218

BigQuery:

SELECT 
  UPPER(CAST('hello' as BYTES)) as upper_byte, 
  TYPEOF(CAST('hello' as BYTES)) as type_upper_byte, 
  UPPER('hello') AS upper_str, 
  TYPEOF(UPPER('hello')) as type_upper_str;"

+------------+-----------------+-----------+----------------+
| upper_byte | type_upper_byte | upper_str | type_upper_str |
+------------+-----------------+-----------+----------------+
|   SEVMTE8= | BYTES           | HELLO     | STRING         |
+------------+-----------------+-----------+----------------+

DuckDB:

D SELECT UPPER(CAST('hello' as BLOB)) as upper_byte, TYPEOF(CAST('hello' as BLOB)) as type_upper_byte;
Binder Error:
No function matches the given name and argument types 'upper(BLOB)'. You might need to add explicit type casts.
        Candidate functions:
        upper(VARCHAR) -> VARCHAR

D SELECT UPPER('hello') AS upper_str;
┌───────────┐
│ upper_str │
│  varchar  │
├───────────┤
│ HELLO     │
└───────────┘

[VaggelisD]

Nice abstraction @toriwei! Left a couple comments:

[VaggelisD]

Resolving the comments because of similar discussions in the LOWER(...) PR with @georgesittas

[georgesittas]

Gonna clean this up