chore: Expose puffin blob constructor (#1320)

## Which issue does this PR close?

This PR expose public construction function for puffin blob, as
discussed in the linked issue.
The main motivation is: puffin blob is supposed to hold any type, so
should be public-ly accessible by developers.

- Closes #1311

## Are these changes tested?

This PR is a no-op change, I verified compilation passes through on my
end.

Author: dentiny

crates/iceberg/src/puffin/blob.rs

@@ -17,13 +17,15 @@
 
 use std::collections::HashMap;
 
+use typed_builder::TypedBuilder;
+
 /// A serialized form of a "compact" Theta sketch produced by the Apache DataSketches library.
 pub const APACHE_DATASKETCHES_THETA_V1: &str = "apache-datasketches-theta-v1";
 /// A serialized form of a deletion vector.
 pub const DELETION_VECTOR_V1: &str = "deletion-vector-v1";
 
 /// The blob
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Clone, TypedBuilder)]
 pub struct Blob {
     pub(crate) r#type: String,
     pub(crate) fields: Vec<i32>,

crates/iceberg/src/puffin/test_utils.rs

@@ -98,14 +98,14 @@ pub(crate) fn uncompressed_metric_blob_0_metadata() -> BlobMetadata {
 }
 
 pub(crate) fn blob_0() -> Blob {
-    Blob {
-        r#type: METRIC_BLOB_0_TYPE.to_string(),
-        fields: METRIC_BLOB_0_INPUT_FIELDS.to_vec(),
-        snapshot_id: METRIC_BLOB_0_SNAPSHOT_ID,
-        sequence_number: METRIC_BLOB_0_SEQUENCE_NUMBER,
-        data: METRIC_BLOB_0_DATA.as_bytes().to_vec(),
-        properties: HashMap::new(),
-    }
+    Blob::builder()
+        .r#type(METRIC_BLOB_0_TYPE.to_string())
+        .fields(METRIC_BLOB_0_INPUT_FIELDS.to_vec())
+        .snapshot_id(METRIC_BLOB_0_SNAPSHOT_ID)
+        .sequence_number(METRIC_BLOB_0_SEQUENCE_NUMBER)
+        .data(METRIC_BLOB_0_DATA.as_bytes().to_vec())
+        .properties(HashMap::new())
+        .build()
 }
 
 pub(crate) const METRIC_BLOB_1_TYPE: &str = "some-other-blob";
@@ -142,14 +142,14 @@ pub(crate) fn zstd_compressed_metric_blob_1_metadata() -> BlobMetadata {
 }
 
 pub(crate) fn blob_1() -> Blob {
-    Blob {
-        r#type: METRIC_BLOB_1_TYPE.to_string(),
-        fields: METRIC_BLOB_1_INPUT_FIELDS.to_vec(),
-        snapshot_id: METRIC_BLOB_1_SNAPSHOT_ID,
-        sequence_number: METRIC_BLOB_1_SEQUENCE_NUMBER,
-        data: METRIC_BLOB_1_DATA.as_bytes().to_vec(),
-        properties: HashMap::new(),
-    }
+    Blob::builder()
+        .r#type(METRIC_BLOB_1_TYPE.to_string())
+        .fields(METRIC_BLOB_1_INPUT_FIELDS.to_vec())
+        .snapshot_id(METRIC_BLOB_1_SNAPSHOT_ID)
+        .sequence_number(METRIC_BLOB_1_SEQUENCE_NUMBER)
+        .data(METRIC_BLOB_1_DATA.as_bytes().to_vec())
+        .properties(HashMap::new())
+        .build()
 }
 
 pub(crate) const CREATED_BY_PROPERTY_VALUE: &str = "Test 1234";