feat: Safer PartitionSpec & SchemalessPartitionSpec (apache#645)

* SchemalessPartitionSpec

* Traits -> Enum

* Remove PartitionSpec enum

* Address comments

Author: c-thiel

crates/catalog/memory/src/catalog.rs

@@ -283,7 +283,7 @@ mod tests {
     use std::iter::FromIterator;
 
     use iceberg::io::FileIOBuilder;
-    use iceberg::spec::{NestedField, PartitionSpec, PrimitiveType, Schema, SortOrder, Type};
+    use iceberg::spec::{BoundPartitionSpec, NestedField, PrimitiveType, Schema, SortOrder, Type};
     use regex::Regex;
     use tempfile::TempDir;
 
@@ -355,7 +355,7 @@ mod tests {
 
         assert_eq!(metadata.current_schema().as_ref(), expected_schema);
 
-        let expected_partition_spec = PartitionSpec::builder(expected_schema)
+        let expected_partition_spec = BoundPartitionSpec::builder((*expected_schema).clone())
             .with_spec_id(0)
             .build()
             .unwrap();
@@ -365,7 +365,7 @@ mod tests {
                 .partition_specs_iter()
                 .map(|p| p.as_ref())
                 .collect_vec(),
-            vec![&expected_partition_spec]
+            vec![&expected_partition_spec.into_schemaless()]
         );
 
         let expected_sorted_order = SortOrder::builder()

crates/catalog/sql/src/catalog.rs

@@ -781,7 +781,7 @@ mod tests {
     use std::hash::Hash;
 
     use iceberg::io::FileIOBuilder;
-    use iceberg::spec::{NestedField, PartitionSpec, PrimitiveType, Schema, SortOrder, Type};
+    use iceberg::spec::{BoundPartitionSpec, NestedField, PrimitiveType, Schema, SortOrder, Type};
     use iceberg::table::Table;
     use iceberg::{Catalog, Namespace, NamespaceIdent, TableCreation, TableIdent};
     use itertools::Itertools;
@@ -874,10 +874,11 @@ mod tests {
 
         assert_eq!(metadata.current_schema().as_ref(), expected_schema);
 
-        let expected_partition_spec = PartitionSpec::builder(expected_schema)
+        let expected_partition_spec = BoundPartitionSpec::builder(expected_schema.clone())
             .with_spec_id(0)
             .build()
-            .unwrap();
+            .unwrap()
+            .into_schemaless();
 
         assert_eq!(
             metadata