feat: provide service to automatically validate DB migrations in the CI pipeline (#240)

Description

• Create an HTTP server providing an API to create clones and run DB migrations

Related issue

#240

Examples

CI Checker configuration

dle:
  url: "https://dblab.domain.com"
  verificationToken: "dle_secret_token"
platform:
  url: "https://postgres.ai/api/general"
  accessToken: "platform_secret_token"
  enablePersonalTokens: true
source:
  type: "github"
  token: "vcs_secret_token"
runner:
  image: "postgresai/migration-runner:latest"

POST /migration/run

curl --location --request POST "${CI_ENDPOINT}" \
--header "Verification-Token: ${SECRET_TOKEN}" \
--header 'Content-Type: application/json' \
--data '{"source":{"owner":"postgres-ai","repo":"runci","ref":"refs/heads/240-debug-ci"},"actor":"artyom","db_name":"test","commands":["sqitch deploy","env","echo 'Migration has been completed'"],"migration_envs":["DATABASE_LAB_CI=true"]}'

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes, specifications reflect those changes and they have been reviewed OR there are no API changes

Closes #240