Implement ListMultipartUploads (#171)

Implement ListMultipartUploads, also refactor ListObjects and ListObjectsV2.

It took me some times as I wanted to propose the following things:
  - Using an iterator instead of the loop+goto pattern. I find it easier to read and it should enable some optimizations. For example, when consuming keys of a common prefix, we do many [redundant checks](https://git.deuxfleurs.fr/Deuxfleurs/garage/src/branch/main/src/api/s3_list.rs#L125-L156) while the only thing to do is to [check if the following key is still part of the common prefix](https://git.deuxfleurs.fr/Deuxfleurs/garage/src/branch/feature/s3-multipart-compat/src/api/s3_list.rs#L476).
  - Try to name things (see ExtractionResult and RangeBegin enums) and to separate concerns (see ListQuery and Accumulator)
  - An IO closure to make unit tests possibles.
  - Unit tests, to track regressions and document how to interact with the code
  - Integration tests with `s3api`. In the future, I would like to move them in Rust with the aws rust SDK.

Merging of the logic of ListMultipartUploads and ListObjects was not a goal but a consequence of the previous modifications.

Some points that we might want to discuss:
  - ListObjectsV1, when using pagination and delimiters, has a weird behavior (it lists multiple times the same prefix) with `aws s3api` due to the fact that it can not use our optimization to skip the whole prefix. It is independant from my refactor and can be tested with the commented `s3api` tests in `test-smoke.sh`. It probably has the same weird behavior on the official AWS S3 implementation.
  - Considering ListMultipartUploads, I had to "abuse" upload id marker to support prefix skipping. I send an `upload-id-marker` with the hardcoded value `include` to emulate your "including" token.
  - Some ways to test ListMultipartUploads with existing software (my tests are limited to s3api for now).

Co-authored-by: Quentin Dufour <quentin@deuxfleurs.fr>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/171
Co-authored-by: Quentin <quentin@dufour.io>
Co-committed-by: Quentin <quentin@dufour.io>

src/api/s3_xml.rs

@@ -141,6 +141,60 @@ pub struct CompleteMultipartUploadResult {
 	pub etag: Value,
 }
 
+#[derive(Debug, Serialize, PartialEq)]
+pub struct Initiator {
+	#[serde(rename = "DisplayName")]
+	pub display_name: Value,
+	#[serde(rename = "ID")]
+	pub id: Value,
+}
+
+#[derive(Debug, Serialize, PartialEq)]
+pub struct ListMultipartItem {
+	#[serde(rename = "Initiated")]
+	pub initiated: Value,
+	#[serde(rename = "Initiator")]
+	pub initiator: Initiator,
+	#[serde(rename = "Key")]
+	pub key: Value,
+	#[serde(rename = "UploadId")]
+	pub upload_id: Value,
+	#[serde(rename = "Owner")]
+	pub owner: Owner,
+	#[serde(rename = "StorageClass")]
+	pub storage_class: Value,
+}
+
+#[derive(Debug, Serialize, PartialEq)]
+pub struct ListMultipartUploadsResult {
+	#[serde(serialize_with = "xmlns_tag")]
+	pub xmlns: (),
+	#[serde(rename = "Bucket")]
+	pub bucket: Value,
+	#[serde(rename = "KeyMarker")]
+	pub key_marker: Option<Value>,
+	#[serde(rename = "UploadIdMarker")]
+	pub upload_id_marker: Option<Value>,
+	#[serde(rename = "NextKeyMarker")]
+	pub next_key_marker: Option<Value>,
+	#[serde(rename = "NextUploadIdMarker")]
+	pub next_upload_id_marker: Option<Value>,
+	#[serde(rename = "Prefix")]
+	pub prefix: Value,
+	#[serde(rename = "Delimiter")]
+	pub delimiter: Option<Value>,
+	#[serde(rename = "MaxUploads")]
+	pub max_uploads: IntValue,
+	#[serde(rename = "IsTruncated")]
+	pub is_truncated: Value,
+	#[serde(rename = "Upload")]
+	pub upload: Vec<ListMultipartItem>,
+	#[serde(rename = "CommonPrefixes")]
+	pub common_prefixes: Vec<CommonPrefix>,
+	#[serde(rename = "EncodingType")]
+	pub encoding_type: Option<Value>,
+}
+
 #[derive(Debug, Serialize, PartialEq)]
 pub struct ListBucketItem {
 	#[serde(rename = "Key")]
@@ -432,6 +486,58 @@ mod tests {
 		Ok(())
 	}
 
+	#[test]
+	fn list_multipart_uploads_result() -> Result<(), ApiError> {
+		let result = ListMultipartUploadsResult {
+			xmlns: (),
+			bucket: Value("example-bucket".to_string()),
+			key_marker: None,
+			next_key_marker: None,
+			upload_id_marker: None,
+			encoding_type: None,
+			next_upload_id_marker: None,
+			upload: vec![],
+			delimiter: Some(Value("/".to_string())),
+			prefix: Value("photos/2006/".to_string()),
+			max_uploads: IntValue(1000),
+			is_truncated: Value("false".to_string()),
+			common_prefixes: vec![
+				CommonPrefix {
+					prefix: Value("photos/2006/February/".to_string()),
+				},
+				CommonPrefix {
+					prefix: Value("photos/2006/January/".to_string()),
+				},
+				CommonPrefix {
+					prefix: Value("photos/2006/March/".to_string()),
+				},
+			],
+		};
+
+		assert_eq!(
+			to_xml_with_header(&result)?,
+			"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\
+<ListMultipartUploadsResult xmlns=\"http://s3.amazonaws.com/doc/2006-03-01/\">\
+	<Bucket>example-bucket</Bucket>\
+	<Prefix>photos/2006/</Prefix>\
+	<Delimiter>/</Delimiter>\
+	<MaxUploads>1000</MaxUploads>\
+	<IsTruncated>false</IsTruncated>\
+	<CommonPrefixes>\
+		<Prefix>photos/2006/February/</Prefix>\
+	</CommonPrefixes>\
+	<CommonPrefixes>\
+		<Prefix>photos/2006/January/</Prefix>\
+	</CommonPrefixes>\
+	<CommonPrefixes>\
+		<Prefix>photos/2006/March/</Prefix>\
+	</CommonPrefixes>\
+</ListMultipartUploadsResult>"
+		);
+
+		Ok(())
+	}
+
 	#[test]
 	fn list_objects_v1_1() -> Result<(), ApiError> {
 		let result = ListBucketResult {