Need new endpoint for creating timeline and milestones together

[vikasrohit]

As of now we have separate endpoints for creating timeline and milestone entities which becomes very time consuming when front end tries to create a timeline for an entity e.g. when we are trying to create timeline for a project phase, we have all milestone templates but when we want to create a timeline using those templates, we have to send one request for creating timeline object and then send multiple requests to create milestone for each of the milestone template. We want to reduce that over head by introducing a new endpoint in the project service which can do all of that operations in single call. Currently we have two solutions:

1. Add new endpoint to support bulk milestones e.g. POST /v4/timelines/1234/milestones/createBulk
2. Update existing endpoint to create template with milestones e.g. /v4/timelines to support specifying the milestone in the payload.
3. Accept a new field templateId in POST /v4/timelines and create all the milestones which have the productTemplateId === templateId.

We are inclining towards 2. However, we are still open for any suggestion for handling it in a better way.
We have opted for 3 to make things consistent and easy to understand.

[vikasrohit]

Implemented the functionality by reading the templateId instead of reading the milestones in the request body. This would make things consistent with the way we are handling project and phases.