Remove sourceIdentifier filtering and prepare v0.4.0-beta

[afoote-mitre]

Summary

This PR removes the unsupported sourceIdentifier search filter and bumps the project version to 0.4.0-beta.

Changes

Remove sourceIdentifier Filtering

• Removed sourceIdentifier from accepted /search request parameters.
• Removed its OpenSearch field mapping and input-length configuration.
• Requests containing sourceIdentifier now fail explicitly with 400 INVALID_PARAM.
• Removed the parameter from README documentation, Swagger schemas, request examples, and generated OpenAPI documentation.
• Updated middleware and query-builder tests to remove obsolete behavior while retaining structured-filter coverage.

Primary files:

• utils/constants.js
• controllers/middleware.test.js
• utils/searchQueryBuilder.test.js
• routes/swagger.js
• routes/index.js
• api-docs/openapi.json
• api-docs/openapi.test.js
• README.md

Version Update

• Bumped the project from 0.3.0-beta to 0.4.0-beta.
• Made Swagger derive its version from package.json.
• Added contract coverage to prevent package and OpenAPI versions from drifting.

Primary files:

• package.json
• package-lock.json
• routes/swagger.js
• api-docs/openapi.json
• api-docs/openapi.test.js

Dependabot Status

• Confirmed the dependency tree resolves body-parser@1.20.6, addressing the open 1.20.5 to 1.20.6 Dependabot remediation.
• No redundant package override or additional lockfile dependency update was required.