Add support for children bucket creation

[jujaga]

Description

This PR focuses on implementing the ability to create children buckets without necessarily knowing the raw S3 bucket credentials.

• 83f2ace Resolve all max-len lint warnings
• c4d715b Update OpenAPI spec with createBucketChild and add unit tests
• 1e7c498 Implement createBucketChild endpoint

SHOWCASE-3399

Types of changes

New feature (non-breaking change which adds functionality) Documentation (non-breaking change with enhancements to documentation)

Checklist

• [x] I have read the CONTRIBUTING doc
• [x] I have checked that unit tests pass locally with my changes
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have added necessary documentation (if appropriate)

Further comments

As this PR also does a complete codebase update to remove the max-len lint warnings, there are many inconsequential differences in the changelog. The core changes of this PR can be found in the following files:

• app/src/controllers/bucket.js
• app/src/docs/v1.api-spec.yaml
• app/src/routes/v1/bucket.js
• app/src/validators/bucket.js
• app/tests/unit/controllers/bucket.spec.js
• app/tests/unit/validators/bucket.spec.js

[codeclimate[bot]]

Code Climate has analyzed commit 496d3856 and detected 10 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	3
Duplication	6
Bug Risk	1

The test coverage on the diff in this pull request is 62.2% (50% is the threshold).

This pull request will bring the total coverage in the repository to 65.7% (0.1% change).

View more on Code Climate.

[github-actions[bot]]

Coverage Report

Totals
Statements:	59.18% ( 2731 / 4615 )
Methods:	49.13% ( 309 / 629 )
Lines:	65.75% ( 1641 / 2496 )
Branches:	52.42% ( 781 / 1490 )