Added support for logs pipelines CRUD methods

[hi-artem]

What does this PR do?

Added support for some endpoint available in the Logs Pipeline API (all CRUD methods).

There is no existing issue, but our project datadog_backup is using the library, and one of the next features we plan to add is logs-pipeline backup/restore. Thus the need to implement the following PR. Some other projects can also find it useful.

Description of the Change

Similar to other resources, like Dashboard and Monitors, the CRUD methods are located in lib/dogapi/v1/logs_pipeline.rb, and respective tests in spec/integration/logs_pipeline_spec.rb. The service was added tolib/dogapi/facade.rb to make CRUD methods accessible to the library consumers.

Review checklist (to be filled by reviewers)

• Feature or bug fix MUST have appropriate tests (unit, integration, etc...)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have one changelog/ label attached. If applicable it should have the backward-incompatible label attached.
• PR should not have do-not-merge/ label attached.
• If Applicable, issue must have kind/ and severity/ labels attached at least.

[hi-artem]

I think the pipeline error is due to this - might be wrong though.

[hi-artem]

Updated: yeah, the 1.9 pipeline was failing due to one of the dependency (crack) of webmock, added rexml to its gemfile. I assume rexml is incompatible with 1.9. Anyway, I pinned crack to 0.4.4 and it passed the build.
Let me know if you have different approach to this issue.