Add batch_id to pipeline run batches for tracking and filtering

[Mbeaulne]

TL;DR

Added batch ID tracking to pipeline run batches, allowing users to identify and filter runs that were created together.

What changed?

• Added batch_id field to BatchCreatePipelineRunsResponse that returns a unique identifier for each batch
• Modified batch creation to generate a unique batch ID and inject it into the annotations of all runs in the batch
• Added BATCH_ID as a new system annotation key with support for existence and equality predicates in filter queries
• Enhanced the _mirror_system_annotations function to create searchable system annotations for batch IDs

How to test?

• Create a batch of pipeline runs and verify the response includes a valid UUID batch_id
• Check that all runs in a batch have the same batch_id in their annotations
• Verify that different batches receive different batch IDs
• Test filtering pipeline runs by batch ID using the new system annotation key

Why make this change?

This enables users to track and manage related pipeline runs that were submitted together as a batch, making it easier to monitor, filter, and operate on groups of runs that share a common context or purpose.

[Mbeaulne]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add batch_id to pipeline run batches for tracking and filtering #150 👈 (View in Graphite)
• Extract pipeline run creation logic into reusable method #149
• Add batch pipeline run creation endpoint #148
• master

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