Expose MergeCtx via exporterhelper#QueueBatchSettings (#13742)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Exposes the `MergeCtx` function introduced in
https://github.com/open-telemetry/opentelemetry-collector/pull/13460/files
to `exporterhelper#QueueBatchSettings`. This will allow configuring the
merge context function using `exporterhelper#WithQueueBatch`.

<!-- Issue number if applicable -->
#### Link to tracking issue
Related to #13320 

<!--Describe what testing was performed and which tests were added.-->
#### Testing
N/A

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#### Documentation
N/A

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Author: lahsivjar

.chloggen/mergectx-queuebatchsettings.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: exporter/exporterhelper
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Expose `MergeCtx` in exporterhelper's queue batch settings`
+
+# One or more tracking issues or pull requests related to the change
+issues: [13742]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

exporter/exporterhelper/internal/queuebatch/queue_batch.go

@@ -21,6 +21,7 @@ type Settings[T any] struct {
 	ItemsSizer       request.Sizer[T]
 	BytesSizer       request.Sizer[T]
 	Partitioner      Partitioner[T]
+	MergeCtx         func(context.Context, context.Context) context.Context
 }
 
 // AllSettings defines settings for creating a QueueBatch.
@@ -29,7 +30,6 @@ type AllSettings[T any] struct {
 	Signal    pipeline.Signal
 	ID        component.ID
 	Telemetry component.TelemetrySettings
-	MergeCtx  func(context.Context, context.Context) context.Context
 }
 
 type QueueBatch struct {