Expose revision_number on ModelRevision GQL/REST node

[jopemachine]

Problem

The deployment_revisions table has a per-deployment sequential revision_number column (models/deployment_revision/row.py), but it is not surfaced anywhere on the read path:

• ModelRevisionData (manager/data/deployment/types.py) does not carry revision_number, so DeploymentRevisionRow.to_data() never propagates it.
• RevisionNode DTO (common/dto/manager/v2/deployment/response.py) has no revision_number field.
• ModelRevision GQL type (api/gql/deployment/types/revision.py) likewise omits the field, even though ModelRevisionFilter / ModelRevisionOrderField already accept revision_number as a sort/filter key.

Consequence: clients can sort or filter revisions by revision_number, but the returned objects do not include the number itself, so they cannot display "Revision #N" or order revisions client-side without a separate lookup.

Proposal

Plumb revision_number through the existing read stack:

1. Add revision_number: int to ModelRevisionData.
2. Populate it in DeploymentRevisionRow.to_data() and any direct ModelRevisionData() construction sites.
3. Add revision_number: int to RevisionNode DTO with a description noting it is a per-deployment sequential number.
4. Add revision_number: int to ModelRevision GQL type using gql_added_field(NEXT_RELEASE_VERSION).

Acceptance Criteria

• Querying ModelRevision via GraphQL returns revision_number for each revision.
• REST v2 deployment revision responses include revision_number in their JSON body.
• pants lint, check, and test pass on changed files; existing revision tests still pass.

JIRA Issue: BA-5982