feat: add GET /api/v1/records/:record_id endpoint

[jfcalvo]

Description

This PR adds a new GET /api/v1/records/:record_id endpoint to get specific records.

This feature is necessary to render a specific record when finding for similarity on the UI.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested

(Please describe the tests that you ran to verify your changes. And ideally, reference tests)

• Running tests locally.

Checklist

• I added relevant documentation
• follows the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[github-actions]

The URL of the deployed environment for this PR is https://argilla-quickstart-pr-4039-ki24f765kq-no.a.run.app