feat: support get_field for map literal (#18371)

## Which issue does this PR close?



## Rationale for this change

currently, get_field for map only supports column.

## What changes are included in this PR?

support get_field for map literal

## Are these changes tested?

UT

## Are there any user-facing changes?

No

Author: chenkovsky

datafusion/functions-nested/src/planner.rs

@@ -18,7 +18,6 @@
 //! SQL planning extensions like [`NestedFunctionPlanner`] and [`FieldAccessPlanner`]
 
 use arrow::datatypes::DataType;
-use datafusion_common::ExprSchema;
 use datafusion_common::{plan_err, utils::list_ndims, DFSchema, Result};
 use datafusion_expr::expr::ScalarFunction;
 use datafusion_expr::expr::{AggregateFunction, AggregateFunctionParams};
@@ -177,9 +176,7 @@ impl ExprPlanner for FieldAccessPlanner {
                         )),
                     )),
                     // special case for map access with
-                    Expr::Column(ref c)
-                        if matches!(schema.data_type(c)?, DataType::Map(_, _)) =>
-                    {
+                    _ if matches!(expr.get_type(schema)?, DataType::Map(_, _)) => {
                         Ok(PlannerResult::Planned(Expr::ScalarFunction(
                             ScalarFunction::new_udf(
                                 get_field_inner(),

datafusion/sqllogictest/test_files/map.slt

@@ -526,23 +526,35 @@ SELECT MAP { 'a': 1, 'b': 3 };
 query error DataFusion error: Arrow error: Cast error: Cannot cast string 'a' to value of Int64 type
 SELECT MAP { 'a': 1, 2: 3 };
 
-# TODO(https://github.com/apache/datafusion/issues/11785): fix accessing map with non-string key
-# query ?
-# SELECT MAP { 1: 'a', 2: 'b', 3: 'c' }[1];
-# ----
-# a
+# accessing map with non-string key
+query T
+SELECT MAP { 1: 'a', 2: 'b', 3: 'c' }[1];
+----
+a
+
+# accessing map with string key
+query I
+SELECT MAP { 'a': 1, 'b': 2, 'c': 3 }['a'];
+----
+1
+
+# accessing map with non-string key in case expression
+query I
+SELECT (CASE WHEN 1 > 0 THEN MAP {'x': 100} ELSE MAP {'y': 200} END)['x']; 
+----
+100
 
 # TODO(https://github.com/apache/datafusion/issues/11785): fix accessing map with non-string key
 # query ?
 # SELECT MAP { MAP {1:'a', 2:'b'}:1, MAP {1:'c', 2:'d'}:2 }[MAP {1:'a', 2:'b'}];
 # ----
 # 1
 
-# TODO(https://github.com/apache/datafusion/issues/11785): fix accessing map with non-string key
-# query ?
-# SELECT MAKE_MAP(1, null, 2, 33, 3, null)[2];
-# ----
-# 33
+# accessing map with non-string key
+query I
+SELECT MAKE_MAP(1, null, 2, 33, 3, null)[2];
+----
+33
 
 ## cardinality