Add initContainer support

[zfalen]

Pull Request

Related issue

Fixes #226

What does this PR do?

• Enables support for initContainers consistent with enablement for containers and volumes etc

Example

I was able to create an initContainer pattern that pulled a .dump file from S3 and mounted it into the Meili pod using the following values:

initContainers:
  - name: aws-copy
    image: amazon/aws-cli
    envFrom:
      - configMapRef:
          name: env-with-s3-creds
    command:
      - "/bin/sh"
      - "-c"
      - aws s3 cp "s3://$S3_BUCKET/meilisearch_dumps" /meili_data/dumps --recursive
    volumeMounts:
      - name: meili-dumps
        mountPath: /meili_data/dumps
volumes:
  - name: meili-dumps
    emptyDir: {}
volumeMounts:
  - name: meili-dumps
    mountPath: /meili_data/dumps
environment:
  MEILI_IMPORT_DUMP: /meili_data/dumps/myClonedDumpFile.dump
  MEILI_ENV: development
  MEILI_MASTER_KEY: someReallyCoolKeyAlsoWookiesRule
  MEILI_NO_ANALYTICS: true

PR checklist

Please check if your PR fulfills the following requirements:

• [ X ] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
• [ X ] Have you read the contributing guidelines?
• [ X ] Have you made sure that the title is accurate and descriptive of the changes?

Thank you so much for contributing to Meilisearch!

[zfalen]

My prettier config messed some formatting up it looks like. We can resolve prior to merge.

[brunoocasali]

@meilisearch sync-manifest

[meili-bors[bot]]

Build succeeded:

• check-chart-manifest-in-sync
• helm-tests
• linter