array_to_string panic on dictionary values

[appletreeisyellow]

Describe the bug

array_to_string function panic's when running a query on data that has dictionary data type. To fix the panic, array_to_string needs to support dictionary type

To Reproduce

1. Use DataFusion CLI:

# in dir datafusion/datafusion-cli
$ cargo build
$ ./target/debug/datafusion-cli

2. Write sample data

CREATE TABLE table1 AS VALUES (1, arrow_cast('foo', 'Dictionary(Int32, Utf8)')), (2, arrow_cast('bar', 'Dictionary(Int32, Utf8)'));

3. Run query

> SELECT array_to_string(array_agg(column2),',') FROM (SELECT column2 FROM table1);
thread 'main' panicked at .../datafusion/datafusion/functions-array/src/string.rs:298:17:
internal error: entered unreachable code
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Expected behavior

> SELECT array_to_string(array_agg(column2),',') FROM (SELECT column2 FROM table1);
+------------------------------------------------------+
| array_to_string(ARRAY_AGG(table2.column2),Utf8(",")) |
+------------------------------------------------------+
| foo,bar                                              |
+------------------------------------------------------+

Additional context

1. Here are the data types that array_to_string currently supports:
   

   datafusion/datafusion/functions-array/src/string.rs

   Lines 63 to 101 in 5912025

   	macro_rules! call_array_function {
   	($DATATYPE:expr, false) => {
   	match $DATATYPE {
   	DataType::Utf8 => array_function!(StringArray),
   	DataType::LargeUtf8 => array_function!(LargeStringArray),
   	DataType::Boolean => array_function!(BooleanArray),
   	DataType::Float32 => array_function!(Float32Array),
   	DataType::Float64 => array_function!(Float64Array),
   	DataType::Int8 => array_function!(Int8Array),
   	DataType::Int16 => array_function!(Int16Array),
   	DataType::Int32 => array_function!(Int32Array),
   	DataType::Int64 => array_function!(Int64Array),
   	DataType::UInt8 => array_function!(UInt8Array),
   	DataType::UInt16 => array_function!(UInt16Array),
   	DataType::UInt32 => array_function!(UInt32Array),
   	DataType::UInt64 => array_function!(UInt64Array),
   	_ => unreachable!(),
   	}
   	};
   	($DATATYPE:expr, $INCLUDE_LIST:expr) => {{
   	match $DATATYPE {
   	DataType::List(_) => array_function!(ListArray),
   	DataType::Utf8 => array_function!(StringArray),
   	DataType::LargeUtf8 => array_function!(LargeStringArray),
   	DataType::Boolean => array_function!(BooleanArray),
   	DataType::Float32 => array_function!(Float32Array),
   	DataType::Float64 => array_function!(Float64Array),
   	DataType::Int8 => array_function!(Int8Array),
   	DataType::Int16 => array_function!(Int16Array),
   	DataType::Int32 => array_function!(Int32Array),
   	DataType::Int64 => array_function!(Int64Array),
   	DataType::UInt8 => array_function!(UInt8Array),
   	DataType::UInt16 => array_function!(UInt16Array),
   	DataType::UInt32 => array_function!(UInt32Array),
   	DataType::UInt64 => array_function!(UInt64Array),
   	_ => unreachable!(),
   	}
   	}};
   	}

2. instead of panic, it would be better to throw an error

[alamb]

I think this is a good first issue as it is well documented , has a test case and the desired behavior is well understood

[EduardoVega]

take